So what Deus just did was a "Forced Sync" now what this does, is that it "Fuses" Deus and Lucifer enabling Deus to utilize Lucifer's abilities that are available to him which I will list soon. With the forced Sync, he gains Enourmous Strength but his defense is reduced 10 fold, meaning if you land a strong enough hit, then you would be able to land some heavy damage unto him.
There are Three mire versions of sync which are:
"Incomplete Sync" "Perfect Sync" and "Neo Sync"