Aah, nice idea. I imagine it would be frustrating if someone packed 6 of them, but in that case, it's just similar to Sundial.
I like it *thumbs up*
Many people are comparing this to phase shield / sundial, but there are some serious differences. If you throw this down with a PA, you are INVINCIBLE for atleast one turn, and requires no foresight. With sundials and phase shields, poison still brings damage and can be afflicted, as well as damaging spells. If you have 2 hp left and a phase shield out, Drain life, Poison, bla bla, can kill you. With this, they cannot. If you have 6in your hand, that's 6 turns of life essentially, not 6 turns of "I hope he doesn't have momentum"