User blog comment:Linathan/Unit Spotlight: Dark Legend Magress/@comment-26140304-20150408231901

NOTE ABOUT MAGRESS'S UBB:

After a bit of testing in Trial EX (Lugina's Trial), I noticed that Magress's UBB did not mitigate Gravion's "Heavy Gravion" attack. Magress's UBB was used last so the 100% damage mitigation was active. This does not seem to be the case for Gravion's ultimate attack as it still managed to deal around 70ish% of my units' HP.

Other players are experiencing this as well. More information in this link.