Greater Blighted Critical
Your critical hit from a spell or spell-like ability afflicts the target with a major spellblight.
Prerequisite: Blighted Critical, Critical Focus, caster level 12th.
Benefit: Whenever you confirm a critical hit with a touch spell, ranged touch spell, or spell-like ability against an opponent, the victim gains a random major spellblight (see page 96).
Special: You can only apply the effects of one critical feat to a given critical hit unless you possess Critical Mastery.
Source: Ultimate Magic, p. 151