Harbor Serpent

+1: Put a +1/+1 counter on up to one target creature. −3: Target creature gains flying and double strike until end of turn. −8: Create X 2/2 white Cat creature tokens, where X is your life total.

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

You gain 7 life.

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) Whenever a creature you control attacks alone, you may tap target creature.

First strike When this creature enters, create a 1/1 white Soldier creature token.

Flying Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)

Flying When this creature enters, target creature gets +2/+2 and gains flying until end of turn.

Creatures your opponents control get -1/-1 until end of turn.