Here is a story about how we localized this tooltip.

The original Korean text is this:
마력 에너지를 극으로 끌어 모아 적들을 섬멸시킬 수 있는 강력한 섬광을 발사합니다. 이 섬광은 최대 약 30m까지 발사됩니다. 이 공격은 일부 특수 몬스터를 제외한 대상에게 100% 확률로 치명상을 유발합니다. 섬멸의 빛 시전 중에는 적에게 아무런 피해도 입지 않습니다.

My BFF (our main QA guy on TERA that is also bilingual) translated it to this:
"This attack has 100% chance to crit, except for some special monsters."

I then jumped in and said, "No no no. We can't say special mobs. That doesn't mean anything. It would just cause player contacts. Figure out something better"

And here is where I dropped the ball. I should have made sure we localized this skill tooltip better.

So, I just asked my favorite author, who happens to be one of our writers on TERA to give this skill tooltip some clarification.

Here is what it will look like after our next maintenance:
"Deal damage to all enemies in front of you, up to 30m, with a very high chance to crit. You are invulnerable while using this skill."