Luckily for Hydra players, plenty of the cards they'll be packing in their decks will be creatures with X in their mana costs, meaning these two creatures will be able to supply tons of mana to help you ramp out enormous Hydras
I think Spellskite would be superior to Dive Down as it is more disruptive, can do so at no mana's cost once in play and has decent defensive application in a race
Its not often that a card destined to be mainly played leading a deck keeps its price, and unless this sees play elsewhere itll likely drop in price, no matter how much hype there is
This will be supported by Brawl, and creates the first opportunity to run double commanders in that format
You can even combo him up with a slew of other cards that can bring him back to your hand, blink him etc
Though Merlin, Rabbit is stronger for card draw, Genie's evasive ensures that without removal or a higher cost Evasive card, he will stay on the field