diff --git a/synthesis_workflow/tasks/circuit.py b/synthesis_workflow/tasks/circuit.py
index 990654c..3e812b9 100644
--- a/synthesis_workflow/tasks/circuit.py
+++ b/synthesis_workflow/tasks/circuit.py
@@ -19,11 +19,11 @@
 from .config import CircuitConfig
 from .config import SynthesisConfig
 from .luigi_tools import copy_params
-from .luigi_tools import GlobalParamTask
 from .luigi_tools import ParamLink
+from .luigi_tools import WorkflowTask
 
 
-class CreateAtlasLayerAnnotations(GlobalParamTask):
+class CreateAtlasLayerAnnotations(WorkflowTask):
     """Create the annotation file for layers from an atlas.
 
     Args:
@@ -72,7 +72,7 @@ def output(self):
         return luigi.LocalTarget(self.layer_annotations_path)
 
 
-class CreateAtlasPlanes(GlobalParamTask):
+class CreateAtlasPlanes(WorkflowTask):
     """Create plane cuts of an atlas.
 
     Args:
@@ -129,7 +129,7 @@ def output(self):
 @copy_params(
     mtypes=ParamLink(SynthesisConfig),
 )
-class SliceCircuit(GlobalParamTask):
+class SliceCircuit(WorkflowTask):
     """Create a smaller circuit .mvd3 file for subsampling.
 
     Args:
diff --git a/synthesis_workflow/tasks/diametrizer.py b/synthesis_workflow/tasks/diametrizer.py
index 244e8a1..d3f8b1b 100644
--- a/synthesis_workflow/tasks/diametrizer.py
+++ b/synthesis_workflow/tasks/diametrizer.py
@@ -23,8 +23,8 @@
 from .config import DiametrizerConfig
 from .config import RunnerConfig
 from .luigi_tools import copy_params
-from .luigi_tools import GlobalParamTask
 from .luigi_tools import ParamLink
+from .luigi_tools import WorkflowTask
 
 
 matplotlib.use("Agg")
@@ -67,7 +67,7 @@ def _plot_models(models_params, models_data, fig_folder="figures", ext=".png"):
 @copy_params(
     nb_jobs=ParamLink(RunnerConfig),
 )
-class BuildDiameterModels(GlobalParamTask):
+class BuildDiameterModels(WorkflowTask):
     """Task to build diameter models from set of cells."""
 
     morphs_df_path = luigi.Parameter(default="morphs_df.csv")
@@ -144,7 +144,7 @@ def _diametrizer(
     return gid, new_path, exception
 
 
-class Diametrize(luigi.Task):
+class Diametrize(WorkflowTask):
     """Task to build diameter models from set of cells."""
 
     morphs_df_path = luigi.Parameter(default="morphs_df.csv")
diff --git a/synthesis_workflow/tasks/synthesis.py b/synthesis_workflow/tasks/synthesis.py
index 189fbb4..9b0bf72 100644
--- a/synthesis_workflow/tasks/synthesis.py
+++ b/synthesis_workflow/tasks/synthesis.py
@@ -28,8 +28,8 @@
 from .config import RunnerConfig
 from .config import SynthesisConfig
 from .luigi_tools import copy_params
-from .luigi_tools import GlobalParamTask
 from .luigi_tools import ParamLink
+from .luigi_tools import WorkflowTask
 
 
 morphio.set_maximum_warnings(0)
@@ -37,7 +37,7 @@
 L = logging.getLogger(__name__)
 
 
-class ApplySubstitutionRules(luigi.Task):
+class ApplySubstitutionRules(WorkflowTask):
     """Apply substitution rules to the morphology dataframe.
 
     Args:
@@ -65,7 +65,7 @@ def output(self):
 @copy_params(
     tmd_parameters_path=ParamLink(SynthesisConfig),
 )
-class BuildSynthesisParameters(GlobalParamTask):
+class BuildSynthesisParameters(WorkflowTask):
     """Build the tmd_parameter.json for synthesis.
 
     Args:
@@ -119,7 +119,7 @@ def output(self):
 @copy_params(
     morphology_path=ParamLink(PathConfig),
 )
-class BuildSynthesisDistributions(GlobalParamTask):
+class BuildSynthesisDistributions(WorkflowTask):
     """Build the tmd_distribution.json for synthesis.
 
     Args:
@@ -168,7 +168,7 @@ def requires(self):
 @copy_params(
     nb_jobs=ParamLink(RunnerConfig),
 )
-class BuildAxonMorphologies(GlobalParamTask):
+class BuildAxonMorphologies(WorkflowTask):
     """Run choose-morphologies to synthesize axon morphologies.
 
     Args:
@@ -232,7 +232,7 @@ def output(self):
     morphology_path=ParamLink(PathConfig),
     nb_jobs=ParamLink(RunnerConfig),
 )
-class Synthesize(GlobalParamTask):
+class Synthesize(WorkflowTask):
     """Run placement-algorithm to synthesize morphologies.
 
     Args:
@@ -265,9 +265,11 @@ def run(self):
         """"""
 
         axon_morphs_path = self.input()["axons"].path
+        out_mvd3 = self.output()["out_mvd3"]
+        debug_scales = self.output()["debug_scales"]
 
         ensure_dir(axon_morphs_path)
-        ensure_dir(self.output().path)
+        ensure_dir(out_mvd3.path)
         ensure_dir(self.apical_points_path)
         ensure_dir(PathConfig().synth_output_path)
 
@@ -288,7 +290,7 @@ def run(self):
             "tmd_parameters": self.input()["tmd_parameters"].path,
             "tmd_distributions": self.input()["tmd_distributions"].path,
             "atlas": CircuitConfig().atlas_path,
-            "out_mvd3": self.output().path,
+            "out_mvd3": out_mvd3.path,
             "out_apical": self.apical_points_path,
             "out_morph_ext": [str(self.ext)],
             "out_morph_dir": PathConfig().synth_output_path,
@@ -301,12 +303,16 @@ def run(self):
         }
 
         run_synthesize_morphologies(
-            kwargs, nb_jobs=self.nb_jobs, debug_scales=self.debug_region_grower_scales
+            kwargs, nb_jobs=self.nb_jobs, debug_scales=debug_scales.path
         )
 
     def output(self):
         """"""
-        return luigi.LocalTarget(self.out_circuit_path)
+        return {
+            "out_mvd3": luigi.LocalTarget(self.out_circuit_path),
+            "out_morphologies": luigi.LocalTarget(PathConfig().synth_output_path),
+            "debug_scales": luigi.LocalTarget(self.debug_region_grower_scales),
+        }
 
 
 @copy_params(
@@ -314,7 +320,7 @@ def output(self):
     tmd_parameters_path=ParamLink(SynthesisConfig),
     nb_jobs=ParamLink(RunnerConfig),
 )
-class AddScalingRulesToParameters(GlobalParamTask):
+class AddScalingRulesToParameters(WorkflowTask):
     """Add scaling rules to tmd_parameter.json."""
 
     scaling_rules_path = luigi.Parameter(default="scaling_rules.yaml")
@@ -356,7 +362,7 @@ def output(self):
     morphology_path=ParamLink(PathConfig),
     nb_jobs=ParamLink(RunnerConfig),
 )
-class RescaleMorphologies(GlobalParamTask):
+class RescaleMorphologies(WorkflowTask):
     """Rescale morphologies for synthesis input."""
 
     rescaled_morphology_path = luigi.Parameter(default="rescaled_morphology_path")
diff --git a/synthesis_workflow/tasks/vacuum_synthesis.py b/synthesis_workflow/tasks/vacuum_synthesis.py
index 5e5f90d..e15b29d 100644
--- a/synthesis_workflow/tasks/vacuum_synthesis.py
+++ b/synthesis_workflow/tasks/vacuum_synthesis.py
@@ -14,8 +14,8 @@
 from .config import RunnerConfig
 from .config import SynthesisConfig
 from .luigi_tools import copy_params
-from .luigi_tools import GlobalParamTask
 from .luigi_tools import ParamLink
+from .luigi_tools import WorkflowTask
 from .synthesis import BuildSynthesisDistributions
 from .synthesis import BuildSynthesisParameters
 
@@ -30,7 +30,7 @@
     nb_jobs=ParamLink(RunnerConfig),
     joblib_verbose=ParamLink(RunnerConfig),
 )
-class VacuumSynthesize(GlobalParamTask):
+class VacuumSynthesize(WorkflowTask):
     """Grow cells in vacuum, for annotation tasks."""
 
     vacuum_synth_morphology_path = luigi.Parameter(default="vacuum_synth_morphologies")
@@ -58,8 +58,8 @@ def run(self):
         else:
             mtypes = self.mtypes
 
-        Path(self.vacuum_synth_morphology_path).mkdir(parents=True, exist_ok=True)
-        morphology_base_path = Path(self.vacuum_synth_morphology_path).absolute()
+        Path(self.output()["out_morphologies"].path).mkdir(parents=True, exist_ok=True)
+        morphology_base_path = Path(self.output()["out_morphologies"].path).absolute()
         vacuum_synth_morphs_df = grow_vacuum_morphologies(
             mtypes,
             self.n_cells,
@@ -69,17 +69,20 @@ def run(self):
             joblib_verbose=self.joblib_verbose,
             nb_jobs=self.nb_jobs,
         )
-        vacuum_synth_morphs_df.to_csv(self.output().path, index=False)
+        vacuum_synth_morphs_df.to_csv(self.output()["out_morphs_df"].path, index=False)
 
     def output(self):
         """"""
-        return luigi.LocalTarget(self.vacuum_synth_morphs_df_path)
+        return {
+            "out_morphs_df": luigi.LocalTarget(self.vacuum_synth_morphs_df_path),
+            "out_morphologies": luigi.LocalTarget(self.vacuum_synth_morphology_path),
+        }
 
 
 @copy_params(
     morphology_path=ParamLink(PathConfig, default="vacuum_morphology_path"),
 )
-class PlotVacuumMorphologies(GlobalParamTask):
+class PlotVacuumMorphologies(WorkflowTask):
     """Plot morphologies to obtain annotations."""
 
     pdf_filename = luigi.Parameter(default="vacuum_morphologies.pdf")
@@ -90,7 +93,7 @@ def requires(self):
 
     def run(self):
         """"""
-        vacuum_synth_morphs_df = pd.read_csv(self.input().path)
+        vacuum_synth_morphs_df = pd.read_csv(self.input()["out_morphs_df"].path)
         ensure_dir(self.output().path)
         plot_vacuum_morphologies(
             vacuum_synth_morphs_df,
diff --git a/synthesis_workflow/tasks/validation.py b/synthesis_workflow/tasks/validation.py
index 0ebc367..9aa5e31 100644
--- a/synthesis_workflow/tasks/validation.py
+++ b/synthesis_workflow/tasks/validation.py
@@ -22,8 +22,8 @@
 from .config import RunnerConfig
 from .config import SynthesisConfig
 from .luigi_tools import copy_params
-from .luigi_tools import GlobalParamTask
 from .luigi_tools import ParamLink
+from .luigi_tools import WorkflowTask
 from .synthesis import AddScalingRulesToParameters
 from .synthesis import BuildSynthesisDistributions
 from .synthesis import ApplySubstitutionRules
@@ -37,7 +37,7 @@
 @copy_params(
     ext=ParamLink(PathConfig),
 )
-class ConvertMvd3(GlobalParamTask):
+class ConvertMvd3(WorkflowTask):
     """Convert synthesize mvd3 file to morphs_df.csv file.
 
     Args:
@@ -51,7 +51,7 @@ def requires(self):
     def run(self):
         """"""
         synth_morphs_df = convert_mvd3_to_morphs_df(
-            self.input().path, PathConfig().synth_output_path, self.ext
+            self.input()["out_mvd3"].path, PathConfig().synth_output_path, self.ext
         )
 
         synth_morphs_df.to_csv(self.output().path, index=False)
@@ -61,7 +61,7 @@ def output(self):
         return luigi.LocalTarget(PathConfig().synth_morphs_df_path)
 
 
-class PlotMorphometrics(luigi.Task):
+class PlotMorphometrics(WorkflowTask):
     """Plot morphometric."""
 
     morph_type = luigi.ChoiceParameter(
@@ -128,7 +128,7 @@ def output(self):
 @copy_params(
     nb_jobs=ParamLink(RunnerConfig),
 )
-class PlotDensityProfiles(GlobalParamTask):
+class PlotDensityProfiles(WorkflowTask):
     """Plot density profiles of neurites in an atlas.
 
     Args:
@@ -151,7 +151,7 @@ def run(self):
         """"""
 
         circuit = load_circuit(
-            path_to_mvd3=self.input().path,
+            path_to_mvd3=self.input()["out_mvd3"].path,
             path_to_morphologies=PathConfig().synth_output_path,
             path_to_atlas=CircuitConfig().atlas_path,
         )
@@ -175,7 +175,7 @@ def output(self):
     nb_jobs=ParamLink(RunnerConfig),
     joblib_verbose=ParamLink(RunnerConfig),
 )
-class PlotCollage(GlobalParamTask):
+class PlotCollage(WorkflowTask):
     """Plot collage.
 
     Args:
@@ -225,7 +225,7 @@ def output(self):
     nb_jobs=ParamLink(RunnerConfig),
     joblib_verbose=ParamLink(RunnerConfig),
 )
-class PlotSingleCollage(GlobalParamTask):
+class PlotSingleCollage(WorkflowTask):
     """Plot collage for single mtype.
 
     Args:
@@ -253,7 +253,7 @@ def requires(self):
     def run(self):
         """"""
         circuit = load_circuit(
-            path_to_mvd3=self.input()["synthesis"].path,
+            path_to_mvd3=self.input()["synthesis"]["out_mvd3"].path,
             path_to_morphologies=PathConfig().synth_output_path,
             path_to_atlas=CircuitConfig().atlas_path,
         )
@@ -282,7 +282,7 @@ def output(self):
 @copy_params(
     mtypes=ParamLink(SynthesisConfig),
 )
-class PlotScales(GlobalParamTask):
+class PlotScales(WorkflowTask):
     """Plot scales.
 
     Args:
@@ -348,7 +348,7 @@ def output(self):
     morphology_path=ParamLink(PathConfig),
     nb_jobs=ParamLink(RunnerConfig),
 )
-class PlotPathDistanceFits(GlobalParamTask):
+class PlotPathDistanceFits(WorkflowTask):
     """Plot collage for single mtype.
 
     Args:
diff --git a/synthesis_workflow/tools.py b/synthesis_workflow/tools.py
index c73d346..1963c2e 100644
--- a/synthesis_workflow/tools.py
+++ b/synthesis_workflow/tools.py
@@ -167,7 +167,7 @@ def _wrap_worker(_id, worker, logger_kwargs=None):
             if file_handler is None:
                 # Setup file name
                 log_file = logger_kwargs.get("log_file", worker.__class__.__name__)
-                log_file = str(Path(log_file).with_suffix("")) + f"-{_id}.log"
+                log_file = str(Path(log_file).with_suffix("") / f"scale-{_id}.log")
                 ensure_dir(log_file)
 
                 # Setup log formatter