Pretty much everyone who's got a Midas-based OC probably made this their semblance too, so sorry for unoriginality!
On touch, Icter can slowly cover anything in an unbreakable gold-colored layer. Not only is this useful for immobilising enemies, but it also helps fortify his weapons. He can only use it on one object per hand and the effect disappears immediately when he takes his hand off of it.
By striking the same spot over and over again, she can exponentially increase the force in each consecutive strike! Eg. By tapping her finger against the same spot on a wall for about 50+ times, she can easily bring it down!
The damage accumulation resets when she hits anything different of course, so in a fight with her, it's much wiser to block her 5th punch with your face than to let it hit your arm again like the last 4 times!
We've had disguise Semblances before, but Yuki's Semblance lets her fully change her appearance, voice, and outfit to match anyone she's seen before. With this ability, she and her fellow Zodiac allies managed to kidnap Atlas huntress Sandra O'Dile before inauguration and sneak into Team BISC. When her identity was discovered by team leader Brandeis Cygnette, Yuki had to switch gears and kidnap Brandeis, taking her place instead and returning the unconscious Sandra to Team BISC.
Her cover was blown for the final time by teammates Icter Goldman and Ciel Soleil, forcing her to retreat from Atlas after causing significant social upheaval.
Of course, with Brandeis being inspired by Swan Princess Odette, it was only natural to bring in an allusion to Odette's evil doppelganger Odile (hence Yuki's initial cover as Sandra O'Dile)