Fair enough but you currently have got a lot of 5 & 6 drops and only a bit of mana-ramp.
It seems that most of your come- back-in-to-play creatures come into play on the next turn, a lot of your other stuff is return to hand not battlefield so you would have to cast it again - this all seems really mana-intensive.
I would have thought anything cheaper than 6mana that brings a token with it, any returns to battlefield effect (undying or persist) or blinks itself (e.g. lands such as
ghost town,
undiscovered paradise) or others (
conjurer's closet) would work faster.
With the undying creatures when they die for the second time you could return them from the grave and cast them again. Then in the meantime you will have chump-blockers to preserve your life total whilst you get stuff together to mill.
It's the same with the two sac & ramp creatures I mentioned above, they both bring in one or two other permanents (basic land) when they die which will then further activate your Altar and in the meantime they provide some protection so that's three functions from one cheap card.
Without an in-depth analysis my initial impression is that any weeny / aggro deck or deck with flying/evasion with kill you before you really get going.
Maybe the best thing is to try it out on-line with Cockatrice (or similar) or play test it with friends.