Halo Fountain and Incubation Druid do not have summoning sickness.
Incubation Druid has at least one +1/+1 counter on it.
({1} magic symbol) available.
Steps
Activate Karn by paying ({1} magic symbol) , causing Halo Fountain to become an artifact creature until end of turn.
Activate Incubation Druid's first ability by tapping it, adding ({W} magic symbol) ({W} magic symbol) ({W} magic symbol) .
Activate Halo Fountain's second ability by paying ({W} magic symbol) ({W} magic symbol) , tapping it and untapping it and Incubation Druid, causing you to draw a card.