Satangel

It's not the giant frog Dagon as he does not block nor counter and I don't think Dagon has a combo move, he probably means the second time you face of Dante in the small bedroom.

- What you can do is Snatch from a close/medium distance, Dante should roll then counter with a Stinger which you should dodge with a roll(never jump, he counters it with the Shotgun). Make sure you have a Charge Shot ready anytime, level 3 is the best since it does massive damage.

- Snatch again, this time if you manage to catch him, do whatever Combo you like with the Sword but do not finish it(stop before doing the last hit), Snatch again then do another Combo without finishing it, Snatch once more and hit him once with the sword then do a High Roller which sends both of you in the air, here I advise you to release the Charge Shot you've stored while Dante falls as quick as possible(to late and he might dodge).

- Repeat the above steps and you have an easy time. However when he changes into Royal Guard style(the blocking style) just run up to him then Buster like crazy, he can't block a Buster and won't counter while in Royal Guard mode.

- Whenever you are trapped in a Combo, activate the Devil Trigger which should blast you out of it and stun Dante, this is a good time to Buster Dante. Deactivate the DT when you're done with the Buster to save it up for another time you are trapped in a Combo.

- Whenever Dante is ready to shot you(he usually jumps backwards) release the Charge Shot in his face as he won't dodge plus he gets cancelled.

- Whenever he uses Lucifer(red, explosive swords) just run until he uses Rebellion(the sword) or Gilgamesh(the gauntlets and boots) again. Whenever you see him opening the Suitcase, run as far as possible or try to cancel it with a Charge Shot.

I think I covered most situations with this now, hope this helped you beating Dante.