Einherjar has no real requirements to enter, you need to just be level 60 at the very least. However it is still one of the most challenging events in the game.

In Einherjar the objective is to clear waves of enemies, and a boss enemy in a single chamber. But you only have 30 minutes to do so successfully. All monsters link and have a somewhat wide link range, so puller's are reccomended to pull with familiar's if possible. (We will normally always have atleast 1 bst present who can pull)

Things you might want to bring:
Regen drinks
Refresh drinks
Attack food
Reraise Items
Pet food/Dawn muslim(Pup, Bst, Smn, and Drg)

Since the battlefield is only 30 minutes things will start off pretty fast. The normal strategy we use is to have the bst puller pull the entire first wave (~20 monsters or so), normally an eva pet like Dipper Yuly or Faithful Falcor will work just fine, any bst doing this should have no trouble keeping their pet alive.

Basically what everyone's going to do is zerg down the first wave as fast as possible, after the initial pull myself or another will look for the special nm on the floor (Tiger, Sheep, Black bird, Red bird) and kill it. Each of these has a specific effect on the chamber that is beneficial to us.