Seedcradle Witch and Wirewood Channeler on the battlefield.
Wirewood Channeler does not have summoning sickness.
There are at least four Elves on the battlefield.
({GW} magic symbol) available.
Steps
Activate Wirewood Channeler by tapping it, adding at least ({G} magic symbol) ({G} magic symbol) ({G} magic symbol) ({G} magic symbol) or ({W} magic symbol) ({W} magic symbol) ({W} magic symbol) ({W} magic symbol) .
Activate Seedcradle Witch by paying ({2} magic symbol) ({G} magic symbol) ({W} magic symbol) , untapping Wirewood Channeler and giving it +3/+3 until end of turn.
Repeat.
If there are at least five Elves on the battlefield, this combo nets infinite colored mana.