DotA 6.77b Map with Unreleased Heroes - Information taken directly from object files (DotA 6.77b). At least we know IceFrog is caring about unused models.
List of Unreleased Heroes
H0E1 Mortar Team
N0M9 Wyvern Outrider
H0DL Ghost Revenant
Note: In-game, type -clear, hereoes will spawn at center of map
List of things that do not work
Mortar Team's first three skills do nothing. Flash Bomb provides only an effect. Siege Form will crash the map if you buy an Orb Effect.
Ghost Revenant's Exhaustion - Actually is a global Thunder Clap.
P.S. None of this information is from beta version, it's in the current public versions - it is made 100% accessible to the public. It's 'leaked' because it wasn't shown in the map and selectable, but it's not leaked because it's in the public versions. Anyone can read it if they know how to. Simply look at the unit text file, download at this place.
P.P.S. What exactly is "OMG LION TEST" [h05N]? O_O
Download the heroes guides in PDF here.
DotA 6.77b Map with Unreleased Heroes download link: