At the beginning of your end step, Toxrill's first ability triggers, putting a slime counter on each creature your opponents control.
Because your opponents' creatures are now 0/0 due to Maha and Toxrill's static effects, the creatures die as a state-based action due to having zero toughness unless there is an effect boosting their toughness.
Repeat during each of your end steps.

Reduce the toughness of creatures opponents control to 0 on each of your turns

Toxrill, the Corrosive

Maha, Its Feathers Night

At the beginning of your end step, Toxrill's first ability triggers, putting a slime counter on each creature your opponents control.
Because your opponents' creatures are now 0/0 due to Godhead of Awe and Toxrill's static effects, the creatures die as a state-based action due to having zero toughness.
Repeat during each of your end steps.

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