Summon ally unit/Transform self/Transform enemy unit into ally unit

"Transform" and "Promotion" are both representative of when a unit changes, but Transformation is not consistent. Here is a table of the behaviors of transformations and promotions.

Unit Ability Death Square?
Dryad Transform enemy Yes
Sapling Transform into Tree No
SoulKeeper Transform enemy Yes
Vampire Transform into Bat Yes
Gemini Transform into GeminiTwin Yes
Prince Transform into King No
Slime Transform into GiantSlime No
Phoenix Transform into PhoenixEgg Yes
PhoenixEgg Transform into Phoenix No
Envy Transform into enemy Yes
(minions) Promotes into _____ No
Sylph, AirElemental Promotes into _____ No
Hostage Rescue No
Comet Destroy self Yes
LifeStone Destroy self Yes

Trivia Edit

The sound effects and visuals for promotion/transformation are not quite consistent either. "Custom" means a sound that is made specifically for that unit. As you can see, in most cases transforming and promoting are interchangeable.

Unit Ability Sound Visual
Dryad Transform enemy Custom saplify (normal)
Sapling Transform into Tree (promotion) (promotion)
SoulKeeper Transform enemy Custom ghostify (normal)
Vampire Transform into Bat Summon Grey magic effect
Gemini Transform into GeminiTwin Custom split Grey magic effect
Prince Transform into King (promotion) (promotion)
Slime Transform into GiantSlime (promotion) (promotion)
Phoenix Transform into PhoenixEgg Death Death of attacker
PhoenixEgg Transform into Phoenix Custom hatch (none)
Envy Transform into enemy (promotion) Cyan magic effect
(minions) Promotes into _____ (promotion) (promotion)
Sylph, AirElemental Promotes into _____ (promotion) (promotion)
Hostage Rescue Custom rescue (normal)
Comet Destroy self Freeze Cyan magic effect
LifeStone Destroy self Custom revive Grey magic effect

See also Edit