I was, for some reason, still thinking about Spider-Verse. This isn't about Spider-Girl, no real complaining here today.
Otto Spidey has Parker's memories, right? That's how he fools everyone. That and they were hit with the Idiot Stick before they started, but neither here nor there. Otto should remember how Peter beat Morlun the first time: Pump himself full of radiation and rely on it to block Morlun's ability to absorb the spider-totemic energy stuff.
Now obviously all these Spider-Folks don't want to get cancer like Peter did (or whatever it was he got from that which prompted The Other storyline), but see, this is a spot where Otto should actually be ahead of Peter. Parker's a biologist, Otto was the nuclear scientist. That was why he built the arms, to handle dangerous materials safely. He should be able to devise some method of replicating it that won't kill everyone sometime after it has saved all their lives.
Orrrrrrrr, they could just go find a Spider-Man who still has the Captain Universe powers he gained during Acts of Vengeance. You know, the powers that let him drop Graviton with one shot, punch the Hulk into orbit, fight Magneto to a standstill, and destroy a Tri-Sentinel augmented by Loki's magic. Go get one of those Spideys. Better yet, get 5, or 20. Then send them after Morlun and his crew. Pretty sure he'll find it difficult to grab hold of someone and drain their life force when that someone can fly and shoot energy blasts. And if he does grab hold, congratulations! he's a second away from being punched to the Moon. Problem solved.
I suppose there could be some issue like the Enigma Force can't leave its universe of origin. So trick the Morluns into that universe. He's not that smart. Eh, maybe they've addressed these ideas already, but I'll never know, unless one of you tells me.