Flask of Arcane Fortification

Flask of Arcane Fortification is a consumable that increases the player's resistance to arcane spells by 35 and health regeneration by 20 every 5 seconds for 2 hrs.

Source
It is created by alchemists with a skill of 375. The components are:

The recipe is discovered while making other potions. When you make potions you have a small chance of learning new flask recipes.