This guy is probably way too good. Especially the exit trigger letting you get him back. Thoughts?

Hmm. I'm reminded of Protean Hulk. But this isn't as strong as some other rare 8-mana artifact creatures like Sundering Titan or Platinum Emperion. It'd be a lot worse if Emrakul, the Aeons Torn was an artifact, but she isn't, so the worst it can get is only something like Blightsteel Colossus or Inkwell Leviathan.

But it's an 8-cost that horrible that you can probably drop for 4 if you're using minerals.

Sure, but you could do something like that in recent sets with two Etherium Sculptor and a Grand Architect, or some such. Not to mention the brokenness that is Master Transmuter, because she's really best left unmentioned.

Uh.. yeah, she looks broken. Ok, since I didn't even give it trample, I think I'll stick. It's a big stompy that can be played by stompy lovers or tricksy artifact lovers, and I've been conviced it's not overpowered.

If it wins every draft, it's your fault :)

I don't know... this looks like a good 5cc creature to me. Sac lands alone should put at least three lands in your graveyard. After that, the card's effect looks on par with the titan cycle. You know, except that the Titan cycle is broken and warps environments and makes it so there are no other reasonable creatures to play that cost 6 (and aren't Wurmcoil Engine).

Um, was that a "It's ok" or "It's a titan" or something else? I'm confused.

He's saying "It's a titan, which is way too strong". I'm not sure what sac-lands he's referring to, though: Arid Mesa and friends are out of Standard, and older formats have even crazier creatures than this. Deepest Delvings is very good, but just one card.

I point at, oh, just about every other card in this set?

Would it be reasonable if I downsized it slightly? 6/7 perhaps? (For a very pleasing 6/7

If you're doing that, you should really remove the word "Affinity", because that's even less what affinity did than before. Just say "~ costs less to cast for each...".

Good point, also less words.

...Not "Casting cost is reduced by for each". "~ costs less to cast for each". See for example Karador, Ghost Chieftain or Blasphemous Act.

Minerals saw no play, so this guy ended up being unplayable. Which is a shame. Might be a 'do not play in limited' card. (Might just be a reject rare)

I'm not sure he's that unplayable. Minerals are certainly unplayable, but there are other reasons to sac lands: Dwarven Miner, (CL05), Cistern, Dweller in Lava. I'd consider playing him against some decks.