I just learned the game this weekend and I am, for some reason, lost on this one. Akuma has the following ability:

R (4+): Once per turn, before a control check is made, that check get -4. Failing this control check will not end the Combat Phase.

What do I do to pay the cost of (4+)?

Make a control check of 4 or greater.

Almost stamp for Scuba. It means make a check at four difficulty (analogous to playing a card) - you may commit foundations to pass the control check, as well.

Thank you both for the information.