That's what I ran into. This was only the tip of the iceberg too. Every turn i made was a creeper. I kill that creeper and another took its place. I eventually just gave up and let the creepers just take stuff out.
And then there was the conga lines of zombies. I swear they were coming out of no where. Add on the witches I could hear but couldn't find until much later... The enderman that was playing chicken with me. The chicken... No clue where the jockey went but... The chicken. And of course the first slime I've even found on the server decided to be here as well. I was honestly surprised I didn't have silverfish after me considering I was in extreme hills.
On top of this, there was a double spawner with a zombie and cave spider combo just above this cave of mobsanity. A zombie spawner at the entrance of this cave, and another cave spider spawner that was waiting for me after I finally cleared this place. Oh, and let's not forget the crazy thunderstorm going on midway through this whole ordeal! It's like it was trying to get me killed by making it really hard to hear them creepers sneaking up on me.
Oh, and of course, despite the mix of creepers and skeletons, not a single one decided to make me a record to pick up. =\
I wish these guys would show up for me in skyblocks so that I could actually do some of the challenges that require them. Instead, they just won't let me cave in peace.
X_x