So RIOT decided to kill AP Trist, it seems.
On the PBE, they lowered Trist's ratio on her jump from .7 to .5, and her 3 from .9 to .7. Before this, I figured AP Trist could still survive, albeit she wouldn't be the burst-God we knew her as. Instead she'd have to get auto attacks off to do much damage. But it seems RIOT decided they don't want her to be built AP, even if it wasn't going to be viable in a high level of play, and no longer was a toxic-burst build.
Tristana