Hm. Perhaps. But that's only if you draw all 6 of them in your deck, right? By itself, it's only 2 turns of ensured survival, given that your permanents aren't destroyed, and you STILL get injured - you just don't drop below 1 health.
A Phase Shield costs 6
. It protects against all attacks except spells for 3 turns.
This costs 4
. It does not protect against any attacks, but it ensures that you do not die for 2 turns.
It may be powerful, like Phase Shield is, but I don't think it's overpowerful. But if you disagree... I may have to change it.