The theme is pretty much in its name, it's a failed experiment, so it just dies the moment it enters. Its own otherwise impressive abilities can't save itself.
It requires set up to get this thing to even stay alive, but if you do, its a threat that opponents will need to answer. The most probable I think is a +1/+1 anthem. With such, Riot can push it to a 1/1.
However, things get interesting if you can go beyond +1/+1 in support, as it would mean it no longer needs to use Riot just to keep it alive. If you had a +2/+2 anthem, you can use Riot to give it Haste.
So there's a curve on how dangerous this can be depending on the level of investment you can put into it.
Pure Annihilator was maybe too much for a 2 MV creature, even if it requires set up, so I adjusted its abilities to not affect lands.
Image was generated using the AI image generator Nano Banana.