Is currently overpowered. Domain, mana generation, utility, and vision give them way too much sway if exploited. and wow can they be exploited (nethers, planar rifts, etc).

reducing the flux gain on sacrifice to 1 would work to bring it more in line with other buildings

Or a dim to use.

dim would certainly help. what I've noticed is that if you put a planar rift next to it, you've effectively reduced the cost of any creature you cast by 2 flux (delayed, of course, but almost always recoverable).

This is a huge advantage, especially when paired with something like a necromancer who effectively can raise as many zombies as there are corpses with no net flux cost. But of course it's also huge in something like base defense where you can throw out a bunch of low cost creatures (not to mention ghost crypt/ancient battlefield), defend your base and still have flux to cast more.

The fact that it can be used to generate 20 flux in a round, the max in a round I've seen was 24, is what kills me. That doesn't seem remotely balanced.

Using it to effectively reduce the cost of your creatures is a big advantage but reasonable and limited for the most part.

This 20 flux thing is really a problem with ancient battle field and ghost crypt don't you think?

Oh I think so. Yesterday I experienced firsthand how crazy this can get. >.>

Ghost Crypt + Alter of Ix + 3 Nether Plasms + Ancient Battlefield. . .

Yeah, I've played Grug. But the issue isn't with Alter of Ix, it's with Ghost crypt.

I couldn't disagree more Red. I think requiring the alter to dim on use would solve a number of issues involving this card.

Not really. When you look at it, you almost universally get less flux out of the altar than you put in. Most creatures cost 2 or more flux. Consequently, you effectively lose flux each time you sacrifice a 3 flux or more creature. Sure, you can sacrifice dying creatures, and can bring them back to the altar from across the battlefield with a planar rift to be sacrificed. But there's also the bit about how if you're playing as Dark Legion and are being overrun, you can at least access a reservoir of flux locked up in your creatures that you'd otherwise be unable to get at, allowing a counter attack.

The issue here really is that you need to prevent an overabundance of creatures that cost less than 2 flux each. That means Nether Plasms, Possessed creatures (fixed with balancing yesterday), and the Ghost Crypt + Ancient Battlefield trick.

Also, you could prevent undead creatures from being sacrificed (or ghosts, like the haunts) or you could prevent the sacrificed creature from leaving a corpse, thus preventing the sacrifice + gather spirits combo.

But looking at all this, the issue with the altar isn't that its ability can be used more than once per turn.

I thought the dim would be an alternative to lowering the health and making other related changes, but you are right, masses of low-cost creatures is a big part of the problem... and the possession change also lends more strength to your argument.