Well, its important to know that Michael Korvac has implied power superior to Odin and other cosmics, but in truth he only has a number of high-end on panel feats, including tooling with the Avengers, killing the Collector and destroying Starhawk to resurrect him just a while after that. Given how easy Korvac dealt with his opponents its safe to say he can handle several heralds at once.
If you go for implied power, he could very well be Cube-being level.