Its exceedingly rare for a Commander deck to get a cycle of brand new cards, and I think they hit it out of the park with this one
even though that mana is restricted to casting your commander, its still the Commander equivalent of a Black Lotus, the most sought-after card in Magic history (well, except for The One Ring)
In short, Ragnarok is totally overpowered, but to actually execute on the meld can be challenging
The melded version isnt a human, but its tokens are bigger and its attack trigger can also be doubled, so why not
In Avacyn Restored , we tried a mechanic called forbidden where cards could be shuffled into your deck, and in Kaladesh , we experimented with a mechanic called invention where you pull in artifact cards from outside the game to your hand
If the target opponent is an illegal target as Tataru Taru's first ability tries to resolve, it won't resolve and none of its effects will happen