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) .
Magus of the Candelabra does not have summoning sickness.
Steps
Activate up to six lands by tapping them, adding at least ({6} magic symbol) .
Activate Magus of the Candelabra by tapping it and paying ({1} magic symbol) due to Agatha of the Vile Cauldron, untapping the six lands.
Activate Staff of Domination's third ability by paying ({3} magic symbol) and tapping it, untapping Magus of the Candelabra.
Activate Staff of Domination's first ability by paying ({1} magic symbol) , untapping it.
Repeat.
Once you have infinite mana, you may use it to activate Staff of Domination's other abilities, or if you have infinite ({R} magic symbol) and ({G} magic symbol) , you may use it to activate Agatha of the Vile Cauldron's ability.
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.