Iframe

Iframe (invulnerability frame) is part of TERA's combat system. Iframe is a skill (or technically part of frames of skill's animation), which makes you (almost) invulnerable to damage. All classes have least one such skills. Iframes are used to dodge an attack you can't move away from or can't block.

On most classes iframe are some form of Backstep or Evasive Roll.

Using iframes correctly is major part of most dungeon's mechanics. The most familiar to player are maybe Argog in Red Refuge, the Kavador in Velik's Hold and Lilith in Lilith's Keep. All bosses have similar stun area attacks that must be iframed at correct time to escape the stun.

List of iframes per class

 * Priest: Backstep
 * Mystic: Teleport Jaunt, Mass Teleport (Apex skill)
 * Sorcerer: Warp Barrier (barrier), Backstep, Teleport Jaunt, Stone Skin (barrier), Implosion (Apex skill)
 * Ninja: Shadow Jump, Decoy Jutsu (teleport), One Thousand Cuts, Smoke Bomb (barrier for group)
 * Archer: Backstep, Breakaway Bolt, Feign Death (only with Talent points allocated)
 * Gunner: Rolling Reload, Command: Recall (barrier), Balder's Vengeance (only immune to damage, not crowd control)
 * Berserker: Evasive Smash, Evasive Roll, Unbreakable (casting animation only)
 * Slayer: Evasive Roll, Backstab (teleport part only)
 * Warrior: Evasive Roll, Death from Above, Backstab (teleport part only), Smoke Flanker (teleport), Blade Frenzy (Apex skill)
 * Reaper: Shadow Step, Retribution (only when floating part), Shrouded Escape (jump only)
 * Valkyrie: Evasion, Backstab (teleport part only)
 * Lancer: Backstep, Divine Protection (Apex only), Guardian Barrier can block anything iframe can and also some things you cannot iframe, like certain wipe mechanics
 * Brawler: Quick Dash, Divine Wrath (while jump)

Technical discussion
TERA has two types of dodges, sometimes called (true) iframe and barrier. Different iframe skills have minor differences which make them work differently in some situations.

For example, it's known that Sorcerer's Warp Barrier, Gunner's Command: Recall, Ninja's Smoke Bomb are implemented as shields which absorb infinite (or least very high) amount of damage, and are not technically iframes.

It is possible to iframe ie. water phase in BRHM with those skills. Another example is Red Refuge's last boss Argog. During the key mechanic "Argog reveals himself" you can escape the stun only with iframe but not with sorcerer's Warp Barrier. Interestingly, Warp Barrier does protect from any normal stun attacks the boss has. Also Reaper's Retribution fails to protect you from Lilith's lighting strike mechanic.