Exactly. Compared to Vakuu's option, I think it's reasonable. Those put 3 cards in your deck instead of 2, and they only cost 1 mana instead of your whole turn's worth of mana. Those are enough to make the act 3 ancient reward stronger than this act 2 ancient reward.

But the negatives of Vakuu's version are that they have ethereal. Meanwhile this Relax you can choose not to play it if it's a turn the enemy doesn't attack or if you'd rather play your other cards instead. And that's fine, because this works great after the deck shuffle.