Historical Rules · 1 October 2009
Rule 702.30a
Official source text from the 1 October 2009 Rules release
Kicker is a static ability that functions while the spell is on the stack. "Kicker [cost]" means "You may pay an additional [cost] as you cast this spell." The phrase "Kicker [cost 1] and/or [cost 2]" means the same thing as "Kicker [cost 1], kicker [cost 2]." Paying a spell's kicker cost(s) follows the rules for paying additional costs in rules 601.2b and 601.2e-g.