Pain Amplifiers All non-vehicle enemy units within 12" of a Talos Pain Engine or a Cronos Parasite Engine from the Carnival of Pain have their Toughness characteristic reduced by one.
In addition, friendly units chosen from Codex: Dark Eldar that are within 12" of at least one model in this formation and have one or more pain tokens have their Feel No Pain special rule improved by one - usually to Feel No Pain (4+). A Dark Eldar unit with four or more pain tokens instead has its Feel No Pain special rule improved by two - usually to Feel No Pain (3+).