Gift of Growth
Kicker 
(You may pay an additional as you cast this spell.)
Untap target creature. It gets +2/+2 until end of turn. If this spell was kicked, that creature gets +4/+4 until end of turn instead.
Illustrated by YW Tang
This printing
Prices
If Gift of Growth was kicked, the target creature is untapped before getting +4/+4.
If you copy a kicked spell on the stack, the copy is also kicked. If the copied spell is a permanent spell, the token the copy of that spell becomes when it enters is also kicked.
The kicker ability doesn't let you pay a kicker cost more than once.
If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.
To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions. The spell's mana value remains unchanged, no matter what the total cost to cast it was.
If you put a permanent with a kicker ability onto the battlefield without casting it, you can't kick it.
If a spell's kicker cost was paid, the spell is "kicked."
