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 each opposing creature's toughness to zero during each of your end steps

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.

Combos with "Toxrill, the Corrosive"