SpellBuffCost: 2
Your units get armor piercing and swift strike until your next upkeep. (They ignore armor and deal their combat damage before units and heroes without swift strike.)
Nature protects herself with deadly speed and force.
GreenFeral Magic

Swift Strike Rulings
Combat damage is dealt simultaneously if the attacker and the thing it's attacking both have swift strike. — Sirlin
If swift strike damage kills a unit or hero in combat that does not have swift strike, the non-swift strike unit or hero dies before it gets a chance to deal combat damage. — Sirlin