>>226373
Each model is sold with a set of specially-printed d6es. The dice are colored according to damage affinity, and the symbols represent different kinds of damage; for instance, green dice might represent a weakness to bullets, while blue is for lightning, yellow is for explosives/fire, etc etc. The dice are the same within a certain color–i.e., the yellow dice always have X of Y symbol and W of Z symbol–but each unit has a different combination.
(All this shit would be on a reference card, natch)
When you roll to attack, you roll that unit's dice. If you get a symbol, you do damage, represented by removing that unit's dice; you can either remove 2 of the matching color or 1 of any other color.
Bases, superweapons, and other such things are their own models; they have d8s of the appropriate colors, which have more blank sides, but also have more dice overall.