Greater Scroll of Replenishment

This scroll resembles a replenishment scroll, but is twice the length of that item and confers an increased effect.

Regenerates 450 hit points and 150 mana of the Hero and nearby friendly units over 45 seconds.

Source
Kael, Lady Vashj and Illidan can find one in Gates of the Abyss, chapter 5 of the Frozen Throne alliance campaign, Curse of the Blood Elves.