Replenishment Potion

Regenerates the 150 hit points and 50 mana of the Hero over 30 seconds.

Warcraft: The Roleplaying Game
This light green, syrupy liquid is cast through with dark black specks that seem to crawl and swirl in the mixture.

Lesser Replenishment Potion
This concoction resembles a replenishment potion, but lacks the swirling black flecks. It functions as that potion, but for conferring a reduced effect.

Greater Replenishment Potion
This concoction resembles a replenishment potion, but has both white and black flecks swirling within the mixture. It functions as that potion, although it confers an icreased effect.

Source
Tyrande and Maiev can find one in Shards of the Alliance, chapter 6 of the Frozen Throne sentinels campaign, Terror of the Tides.

Kael and Lady Vashj can find one in A Dark Covenant, chapter 2 of the alliance campaign, Curse of the Blood Elves.