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)
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)
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.