Agatha of the Vile Cauldron has power 5 or greater.
You control up to six lands that can tap to produce at least ({6} magic symbol) .
Candelabra of Tawnos does not have summoning sickness.
Steps
Activate Karn's first loyalty ability by putting a loyalty counter on it, causing Candelabra of Tawnos to become an artifact creature until end of turn.
Activate up to six lands by tapping them, adding at least ({6} magic symbol) .
Activate Candelabra of Tawnos by tapping it and paying ({1} magic symbol) due to Agatha of the Vile Cauldron, untapping the up to six lands.
Activate Staff of Domination's third ability by paying ({3} magic symbol) , untapping Candelabra of Tawnos.
Activate Staff of Domination's first ability by paying ({1} magic symbol) , untapping it.
Repeat from step 2.
Once you have infinite mana, you may use it to activate Staff of Domination's other abilities.
Results
Infinite card draw.
Infinite draw triggers.
Infinite lifegain.
Infinite lifegain triggers.
Infinitely large creatures until end of turn except Agatha of the Vile Cauldron.