When any spell targeting a unit with the Rune Maw is successfully cast, roll a D6. On a roll of 2+, the caster must choose a new target for the spell. If no other target is available (because no other target is in range of all eligible units have already been targeted, for example), then the spell is wasted but still counts as having been cast. Spells that do not specifically target the unit are not affected by the Rune Maw.