Activate Mairsil using Nyx Lotus' ability by tapping it, adding at least ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) .
Activate Mairsil using Horseshoe Crab's ability by paying ({U} magic symbol) , untapping it.
Activate Mairsil using Quicksilver Elemental's ability by paying ({U} magic symbol) , causing it to gain all activated abilities of itself until end of turn.
Repeat.
Results
Infinite mana among colors with which you have devotion.