Raids in Minecraft: how to trigger, survive and win one
every Evoker drops a Totem of Undying, every Ravager a Saddle.

The Totem of Undying saves you from death once: if you hold it when you take fatal damage, it is used up and you survive. It is dropped only by Evokers.
The Totem works only in your main hand or off hand, not in the rest of the inventory, which is why players keep it in the off hand during dangerous fights. When it triggers, it removes your status effects, leaves you with a sliver of health and grants Regeneration II for 45 seconds, Absorption II for 5 seconds and Fire Resistance for 40 seconds.
It does not protect you from falling into the void or from the /kill command. A mob holding a Totem is saved in the same way.
Evokers live in Woodland Mansions and appear in raids, so defeating raids is the usual way to collect several totems.
This item has no crafting recipe.
every Evoker drops a Totem of Undying, every Ravager a Saddle.
It is dropped by Evoker.
Held in either hand, it prevents your death once and gives Regeneration, Absorption and Fire Resistance. Effects: Regeneration (level II · 45 s), Absorption (level II · 5 s) and Fire Resistance (level I · 40 s).
No: only one per inventory slot.
Postmortal (Use a Totem of Undying to cheat death).