For example, Matter has a series of life-drain spells that treat the target as Weak to Matter if you’ve applied Melting to them. (Melting tends to be relatively easy to apply… and additionally, there is a passive that makes Melting checks ignore resistance to Matter!)

Matter also has access to a unique set of passives that trigger non-Matter effects when you use abilities that can apply Melting (note: you don’t actually have to have applied Melting, the ability just has to be able to.) These can work even on Matter immune targets, provided the target isn’t immune to the other effect’s element.

At least only ghosts/inorganics are usually immune in Demon: other roguelikes tend to give immunity out to almost anything that isn’t a humanoid, plant, or animal.