Found portal thing

[themercenary]

I found this portal it in ftb infinity, it was held together by a bunch of red hooded people with black faces.
I approached it and got attacked by a bunch of crusader-looking guardian and huge zombies and fireballs i think? Next thing you know the forest is on fire and im dead. I've been wondering what mod this thing is from and what it's called. I don't have a picture.

 

[Henry Link]

That is an obelisk from Thaumcraft. Once you progress far enough in Thaumcraft you can use them to travel to another dimension where there is a maze and boss fight.

 

[themercenary]

thanks

 

[Inaeo]

There are at least three different bosses within those mazes (only one per portal). Each boss gets spawned with semirandom effects on them, so even though there are only three bosses, fighting the same boss again may end up being a totally different fight.