weird units you can use in scenarios (upgrades do not work for these units unless otherwise stated):

King - The leader of any army, losing one means losing 25 morale and not having any Kings means you suffer King Decay.
Dummy - Training unit that can move only forward 1 space like a Shogi Pawn, promotes to SuperDummy.
SuperDummy - Training unit that can move one space in any direction.
MageDummy - Training unit that can freeze up to 3 spaces forward, but is immobile.
Sapling - The unit placed by a Dryad, grows into a Tree.
Tree - Displacement Immune immobile unit, grown Sapling.
BonePile - Necromancers create these.
StonePillar - Antimagic immobile unit, created by earth elementals.
ChaosPortal - chaos chaos
Sorceress - she lives... run while you still can
PhoenixEgg - Dead phoenix. Upgrades work for this unit.
GeminiTwin - A pre-split Gemini. Upgrades work for this unit.
Blank - Yes, this is actually a unit.