If you are having trouble clearing Hell and Hell mode here is a break down of all Dante's missions with simple methods to get S rank and no damage on them all, especially mission 10 which i know annoys a lot of people. This method can be applied to all difficulties not just Hell and Hell and might even be simpler on other difficulties. I will include timestamps as well so you can go straight to the missions you are having issues with
Hope it helps :)
Mission 10 - 00:29
Mission 11 - 09:21
Mission 12 - 18:41
Mission 16 - 24:47
Mission 17 - 30:48
Mission 18 - 32:51
Mission 19 - 38:15
Getting S rank with V is very simple all you have to do is make sure you take no damage and you are guaranteed an S rank at the end with this method. The other thing you need to do for this is just turn on auto-assist and just start pressing his attack buttons. You can make it even simpler on your thumbs by mapping Griffon and Shadow attacks to trigger buttons and then you just press while reading your book to get DT up faster. If Griffon or Shadow go down at any point just activate your DT they will come back up straight away.
For normal fights I would suggest powering up Griffon and Shadow with DT to make the fight go quicker. However, if you are about to face a difficult/ annoying enemy save your DT to instant revive if one goes down especially for boss fights.
The penalty you would take from using auto-assist would get negated by the x2.00 No damage and x1.20 No continue.This can be done for any modeExplanation and 1st example on Dante Must Die - 00:00
Ranking Results from this method - 16:13
2nd example on HELL AND HELL - 16:53