Each figure in Arcane Legions has up to three keywords associated with it.

Various special abilities and scenario rules apply only to units that possess certain keywords. A unit will get a subfaction keyword if 100% of the figures in a unit belong to that subfaction. A unit will get a descriptor or type keyword if over 80% of the figure hit points on the unit have that descriptor or type. If a unit does not qualify for a descriptor keyword, it gets the default descriptor Mixed; if it does not qualify for a type, it gets the default type Irregulars.

Subfactions

Crusader Han subfaction.
Gallic Roman subfaction. Gallic units can be healed by Grand Druid, and increase the power of King of the Gauls.
Greek Egyptian subfaction. An all-Greek army increases the power of Hellenic Pride.
Imperial Han subfaction.
Slavic Mercenary subfaction (found in Roman boosters).
Xiongnu Mercenary subfaction (found in Egyptian boosters). Xiongnu cavalry units benefit from Stormrider. Non-commander Xiongnu figures can be used on Roman and Egyptian cards in the unit builder without a cost penalty.

Descriptor

Construct Construct units can be healed by Artificer, and are vulnerable to Nature Magic and Demolitionist.
Human Human units are vulnerable to Resentful.
Mixed Mixed units are vulnerable to Specialized and Specialist Leader.
Mythic Mythic units are vulnerable to Nature Magic.
Undead Undead units are vulnerable to Nature Magic and can be healed by Necromancer.

Type

Arcana Arcana units are extremely rare.
Artillery Artillery units are vulnerable to Trample.
Cavalry Cavalry units are vulnerable to Carnivorous and benefit from Stormrider.
Irregulars Irregular units are vulnerable to Specialized and Specialist Leader.
Infantry Infantry units are vulnerable to Trample and benefit from Intuition.