This belongs on a forum, not here. And for the record, antigrav just makes the shot delay and not move with you. This can be useful for getting obnoxiously mobile enemies or ones that shoot back when hit.
We all have our favorite combos, like tech.2 + polyphemis, or brimstone + choco. milk. But some combos just don't have the usefulness.
The worst combo I remember getting was anti-gravity (sorry if that's not the official name), the inner eye, and brimstone. Anti-Grav made the brimstone UNBEARABLE by creating a vortex and laser and waiting for enemy to walk into it. The inner eye just made it longer to fire, (or that could've been coincidental). The bright side was it was able to get good damage on stationary enemies. I died to mom that run.
So what's the worst combo you've ever created? If you have had one, tell us why it was terrible.