Upheaval does allow sick combo, but it isn't that hard to use Twisting Nether without it, so I mostly use it to get the runaway back to the fight instead as using it with Twisting Nether. I would rather charge to them instead of waste Upheaval. After you hit your Twisting Nether, the enemies would most likely to fall back, that's where you should use Upheaval to get them behind your back where you teammates could attack them and have a better chance to chase them down. But be careful and...