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 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.

If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.

If a spell's kicker cost was paid, the spell is "kicked."

The kicker ability doesn't let you pay a kicker cost more than once.

Creatures that enter the battlefield after Keldon Strike Team on the turn it entered the battlefield will have haste as long as it's still on the battlefield. Notably, this includes the Soldier creature tokens it creates if it was kicked.

If Keldon Strike Team leaves the battlefield during combat during the turn it entered the battlefield, any attacking creatures that came under your control this turn will continue to attack, even if they no longer have haste.

Keldon Strike Team's last ability grants itself haste in addition to any other creatures you control.