Might be more simply templated with a cost of .

Also, to bounce a permanent every turn is somewhat insane. Look at the hoop Heidar, Rimewind Master made you jump through to get that; or look at how worried I was about the activation on Arcanis, Vagrant Archmage.

Although I guess you do have the sensible "nonland" clause in there, to prevent the most evil use of this. But still, I shudder at the thought of trying to force any creature-based victory condition through this.

I dropped his p/t to that of Arcanis the Omnipotent. Take it as you will, but you can bounce creatures off of an Unsummon due to Tidespout Tyrant's ability.

I'm pretty sure you won, unless you're super far behind, or your opponent has instant speed removal. When you activate this on turn 5, (I assume you played green/blue to accelerate into this on turn 4, because, well, you should) you can stop 6 creatures. Your opponent probably won't have 6 creatures on turn 4, so instead, you'll send back the three creatures he does have and tap 3 lands, stopping him from being able to play all but his cheapest creatures. From that point on, if your opponent doesn't have instant speed removal, he lost the game.

Tidespout Tyrant's ability is good, but you have to build your deck right to take advantage of it well. I can't just power out to Tidespout, then assume I won... I need to be able to play a lot of spells after that, or have a cheap spell that keeps returning to my hand.

Hopefully this is still powerful, but not slaughtering.