Three Steps Ahead is useful because, while the rates for each of its individual abilities are a bit slower than wed like, the option to use any of them on one card means we can run that many less Cancels, Clones, and Catalogs in the rest of our library
Despite the effect of transforming Battle being a triggered ability , its controller exiles the permanent and then casts it without paying the mana cost , opening up space to interact with Battle on the stack with Make Disappear, or other counterspells, or even to bounce them on the stack, with Venser, Shaper Savant and the like
In a build like this it feels vastly more consistent and potent than something like Bonfire of the Damned
Decayed is a hyper-specific mechanic from Innistrad: Midnight Hunt , and appears solely on Zombie creature tokens
If you copy a permanent spell, that copy becomes a token on the battlefield, but that's not the same as creating a token