Questing Phelddagrif does not have summoning sickness.
Steps
Activate
Questing Phelddagrif by tapping it, adding ({G} magic symbol) .
Market Festival triggers, adding two mana of any color(s).
Activate
Questing Phelddagrif's first ability by paying ({G} magic symbol) , giving it +1/+1 until end of turn and causing an opponent to create a 1/1 Hippo creature token.
The Hippo enters the battlefield, triggering
Suture Priest's second ability, causing the opponent to lose 1 life.
Activate
Questing Phelddagrif by paying ({1} magic symbol) and putting a -1/-1 counter on it, untapping it.
Repeat.
Once you have infinite mana, you may activate
Questing Phelddagrif's third ability to cause any number of opponent to draw infinite cards.
Results
Infinite card draw for any number of opponents.
Infinite colored mana.
Infinite creature tokens for any number of opponents.
Infinite draw triggers for any number of opponents.