Taking damage increases your reaper healing by 1 for 2 seconds. If you take damage again during these 2 seconds, you heal for 1/5 of the damage you took. Immune to damage while under the effects of Vampiric Frenzy.
Incendiary Armor is a craftable Pre-Mechanical Bossesarmor set crafted from Incendiary Alloy, and Cobalt Bar/Palladium Bar. It takes a total of 60 Incendius Alloy, 32 Cobalt/Palladium Bars to craft a full set.