But because historic permanents are so common, this card will likely end up being pretty cheap to play
The ability being dependent on the power of the cards just makes this scalable, and Im sure there is an infinite attack combo in there somewhere that helps get around fog effects
Because it's an alternate cost as well, and only from the hand, it's fairly limiting in terms of combo potential outside of a few fringe examples that are 1-mana versions of effects we already see as outlets (or in the case of Weftstalker Ardent, enablers with a hack to Pirate)
Upcoming MTG Sets Wizards of the Coast shows no signs of slowing down, with several major Magic: The Gathering sets already on the calendar
And while Mercurium has material, your opponent cannot activate any monster effects in their Graveyard, if you have a monster with that same Attribute in YOUR Graveyard
Only Obelisk has protection from enemy cards and effects, and it can still be destroyed by effects that don't declare a target