(3 point Merit)
When you are determined and your mind is set, nothing can thwart you from your goals. Characters using Dementation, Dominate, or any other mind-altering magic, spell, or Thaumaturgy path against your character are at +3 difficulty.
Elder levels of powers like Dementation and Dominate may overwhelm even this resistance. Against Level Six powers, the expenditure of a Willpower point through Iron Will only raises the difficulty of the Discipline roll by two. Against Level Seven powers, the difficulty is increased by only one. Level Eight and higher powers cannot be resisted with Iron Will.
This Merit does not affect Presence or other powers dealing with the emotions. Characters with Willpower scores below 8 cannot take this Merit.
[Vampire the Masquerade: 20th Anniversary Edition p 485]