Awakening Core Meta-Cooler (BT2-106) - Union Force

[Evolve] YY2: "Meta-Cooler" (Play this card on top of the specified card)
[Permanent] If your opponent's life is 4 or less, your Leader Card can activate [Awaken].
[Permanent] All "Meta-Cooler" in your Battle Area gain
[Double Strike] (This card inflicts 2 damage instead of 1 when attacking).