Why wou you chuck Evra before damage is dealt? If Evra is a 35/35 it isnt dying unless deathtouch is involved. Let it hit, gain the life back, then chuck it with Brion to double your life total
Because you only switch with the power, not toughness. There's plenty of cards that have 4+ power. Plus it doesn't have trample so it can still be chump blocked by a 1/1.