Robaran Mercenaries

The whole design hinges on a single word: it copies the activated abilities of your legendary creatures, not their triggered ones, and not the static ones that only read like abilities. That distinction is where the card lives and dies. Give it a legend with a cheap activated engine and you have doubled the number of times you can pull that lever each turn: a vigilant 3/4 that can tap for the same effect the legend taps for, while still holding back on defense. But hand it a board of legends whose text is all triggers and keywords and it sits there doing nothing but blocking, waiting for a partner it never got. The friction that pays for the effect is that it is unconditional and pre-existing: it grabs all activated abilities of all your legends, so a busted mana ability, a game-ending activated combo, or a repeatable tutor all come along, but only if such an ability already lives on a legend you control. That makes it a top-down build-around, rewarding a deck assembled around one or two premium activated abilities you want to fire twice rather than a pile of legendary bodies chosen for their stats. It asks you to read your own creatures' text boxes very carefully before you commit the mana, because the entire payoff is contingent on what those boxes actually say.