Chalice of Blood +10
Apparently it isn’t that hard to survive the 248 damage from upgrading it. 155hp, 92 shielding from self-targeting with wand and Scroll of Challenge halving the damage. (ShPD 2.2.1)
I usually just pop a potion of shielding.
How much shielding does that give?
Don't know the exact numbers, but I'd say about 120 on high levels.
Edit: Just tried it. At max level you get 115.
The wiki gives a table to help. There's a minimum level where you can upgrade the chalice with or without a potion of shielding.