Abyssal Depths - just one entry?

I saw my first abyssal depths in titan grotto and jumped in to see what was down.

After a few minutes got swarmed and died, OK no problem, first time.

But, the entrance is sealed now, I'm above ground and can't get in.

If it's just one-entry (like the old waystones), why have the checkpoints in the depths?

Yeah it's one try. I tried twice and got an end monster that had energy shield aura and resistant to my cold build both times. Chances of that should be so ridiculously low that I don't think it was just chance. Lost to unkillable boss lmao.

In all honesty from what I gathered so far the league mechanic seems like a waste of time. At least before end game. Better to just skip it.