Who do you think would win in a 1v1 between Deathwing and Full power Lei Shen (not the one we fought in throne of thunder the one that took a gigantic supernuke to put down for good)
I reckon Lei Shen. Generally, I think that when very OP things that have uber high power level, the smaller unit wins. Especially since lightning is pretty good against big flying targets and titanic power > dragons, usually.
Deathwing when?
Neltharion the Aspect of Earth? Or the Madness of Deathwing, the very embodiment of Cataclysm?
The latter wins, the former is a closer fight that could maybe go either way.
Deathwing.
Lei Shen himself didn’t somehow fundamentally require the Forge of Origination to kill him. That was just the only way the grossly outnumbered and outmatched tol’vir could effectively kill him and the gigantic mogu/Zandalari army he’d brought to conquer Uldum.
Lei Shen in the raid was as powerful as he’d ever been. He just used to have the might of his entire empire at his back, along with all of the various weapons he’d created using the knowledge garnered from the titan mechanisms beneath the Thundering Mountain and Vale of Eternal Blossoms.
Remember, Xuen put up a fight against Lei Shen for basically an entire month in personal combat before finally succumbing, and the White Tiger is really just a single Wild God, i.e. well below the level of a titan-empowered Dragon Aspect, let alone one that was further empowered and made outright unkillable by the Old Gods as Deathwing had been.