GCD AST Cards, why not?

[Rongway]

The only thing about having the card effects themselves worth the loss of Malefic is it makes it really difficult to make the cards appealing to a solo AST. Ideally, you'd want something that has the flexibility to be both effective in groups and while playing alone, because there is solo content in this game and there are people who would like to have fun while using AST solo.

Card buffs last 15s and there are at least 6 GCDs in a 15s timespan, so if Draw cost a GCD the break even point for a solo card damage buff would be 1/6 or about 16.67%. And this is just the break even point--for it to be a gain the buff has to be higher than this. There really isn't any way to make that work except to carve a solo specific case into the ability effect.