Is 2WW enough to justify 3/2 upside? I want some mechanic to reflect the flavour, and don't want it to be only 2/2 or cost more; it could be 3/1. Originally had mana-activated repeatable damage prevention, but was too fiddly.

Hard to really use, since the extra toughness happens in main1. Very minor benefit it seems to me.

True, it doesn't help much. I switched it in instead of a repeatable ability. But then, 3/2 for 4 CMC is not bad to start with. I could easily make it two (or all): it would let you attack with more impunity but only once, which feels like a fine if small upside.