Norn's Thrummingbird

Modular {x}, Flying
When ~ enters the battlefield, for each {w}{w}
spent to cast it, gain 3 life. For each {u}{u}
spent to cast it, draw a card.
When ~ deals combat damage to a player,
choose one —
• Put a +1/+1 counter on target creature.
• Put a -1/-1 counter on target creature.
• Proliferate.