I don't like this idea too much because of the following:
1) Life doesn't really need another shield, especially one that partially does what an Emerald/Jade Shield can do.
2) It protects against only spell-like and permanent-like effects, leaving you vulnerable against creature-based damage. However, with 6 counters and 2 counters created every time a new creature comes into play (something in which Life is the king in comparison with every other element out there), it makes sure no spell or permanents are ever going to hurt you. In other words, this card is a great extreme in both what it can block and what it can't and this is something I seriously don't like.
3) It is too similar with the Bone Wall effect. Though this is not something bad, there is a HUGE difference at the amount of times a creature is played/generated and those a creature dies.
However, you shouldn't be discouraged. This idea has potential, but it may be better to start again from scratch. Hope I wasn't too harsh; I just try to be helpful here...