Invader used a red spell and became invisible

[eniohideカルロス]

Invader used a red spell and became invisible...

..and a few minutes later when I almost forgot about him, he suddenly appeared behind me and back stab me to the death.

Someone had experienced anything like this?

I just ignored all this time the existence of this spell or that was a cheater?

[Fahrenheit]

Unseen form and assassin's gambit

[fmalfeas]

There's also a DLC item that makes you invisible.

And talismans that only turn you invis in PvP.

[Ceciliantas]

You got tryharded by someone too scared to do arena fights.

Next time that happens, just disconnect and come back.