Tigrex

Haste, menace, trample
Enrage 3 — Whenever Tigrex is dealt 3 or more
damage, it gains first strike until the beginning
of its controller's next upkeep.
Roar 5. (Untap this creature: It deals 1 damage to up
to 5 other target creatures. Tap those creatures. Only use
this ability once per turn and only during your turn.)