Blood Element.

[Pineapple]

I'm sorry that I don't follow your evidence because I've never played MtG, but did its HP-cost cards have turn-by-turn costs? While a card may be "cheaper" than other cards when they are played, there is an 8 card starting hand limit (without hourglasses), so the starting resource of 100 HP isn't really that pertinent as long as you can't kill anyone with 8 cards on the first turn, 12 cards on the third turn, etc. until you reach the point where you can match the speed of the fastest decks in the game. After that, isn't it true that all I have to do is make the cards so that they are cheap until you can kill their opponent, and their cost (which technically increases the earlier you played them) becomes higher than the usual cards in the game when the game usually reaches its finish?

[OldTrees]

There is no need to repeat Magic mistakes.
Especially at 100, not 20, life.

"undercosted put pay life" cards are going to end up either useless (if their other costs are anywhere near reason) or hopelessly imba (I did played Trix deck;))) necropotence, scoop).

There is an inherent flaw in using life as an expendable resoure, in that unlike mana (sorry quanta), you get a full compliment right away, and ALL of it save for 1 last one is absolutely FREE.
Yea, just like that. Pay 99 life to do something that's gonna win me the game? sure. On teh first turn, mate.
(It could even not be lethal with all the SoGs and other stuff around)

Bottom line - no. Tried and tested, very tricky design space that gets degenerate real fast.

Correct and incorrect.
We certainly do not want to repeat Magic mistakes however we can learn from them.
We have already solved a huge design "advantage" of MTG by refusing (in the community) to treat Rarity as a balance tool.

Now lets talk about the "inherent flaw":
Health is not absolutely free. You either have played a gambit or you have packed healing thus are paying quanta, draws and card slots for the advantage.
However health is very cheap as such no powerful cards deserve to use it as a major cost (http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=194977) but only as a slight minor cost (http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=205118).

Bottom line: Blood is one of the hardest costs to balance and should be treated as such.