In Warcraft 3 Night Elf campaign, "Daughters Of The Moon" mission, when you get a part of the map where you get some ballista, and you knock some trees off near the base, you get a Hydralisk from Starcraft to join you in your fight.
Its a really fun thing to check out, orcs, elves, undead and right in the middle, a futuristic Hydralisk.
