Agatha of the Vile Cauldron has power 4 or greater.
You control at least one additional nontoken creature.
Steps
Activate Phyrexian Altar by sacrificing another nontoken creature, adding ({B} magic symbol) .
Activate Kenrith's fifth ability by paying ({B} magic symbol) due to Agatha of the Vile Cauldron, putting the creature card onto the battlefield from your graveyard.