Limited invulnerability potions, aka, LIP potions, make you immune to physical attacks for 6 seconds. If you use them while fighting, bosses won't target you even if you are number 1 on threat.

Where can I buy limited invulnerability potion?

dropped in hinterlands off a level 41 silvermane, sells for 100-150g on my server.

How do you make a potion of invulnerability in candy box 2?

To make an invulnerability potion, put 2,000 candies into the cauldron and mix them. When the counter reaches sixty seconds, it will say "Mixing... too much mixing, your arms are hurting." Click stop, and then put it into a bottle(s).