Who works well with gaurd?

I'm jealous. Guard is one of the most underrated B slots in the game for duelists and walls.

It's a great skill on any duelist to protect from QP/Moonbow and other rapid fire Specials (Slayer's + Heavy Blade/Wrath). For example Guard allows lower bulk units, like Nino, to safely bait QP Moonbow Reinhardt without running Fury in their A slot. Faster armors - like Draug and Amelia - love it as well to keep their impressive defense in place. Guard and Panic Ploy are the premier skills for a Wall to stay up to the meta. So Sheena, Gwendolyn, Lukas, and others love it.

Funny, I just pulled a 5 Star -atk Titania this morning as well. I wish I could be of more help, but some people have been running Guard for GHB, since enemy units start out with less turns of cooldown.