When it comes time for Phyrexian Hydra to have -1/-1 counters placed on it from the damage you prevented on it, then it wont get those counters because of Meliras ability
(Create a token thats a copy of a creature token you control.) Whenever a creature token you control enters, put a +1/+1 counter on this creature
This set includes 1 Black-Red deck of 100 Magic cardswith 1 foil-etched, alternate-art legendary commander card and 99 nonfoil cards, including Lands10 two-sided tokens, a deck box and punchout counters
Bandai One Piece Card Game, Extra Booster, Memorial Collection, EB-01, Box of 24
No further details were revealed about how this would be implemented, but it seems like there will finally be an official competitive scene to challenge players