There are two of this mob in Ikky 4 raid trial. One in the first room on the right (Acolyte position in Ikky 3) and one in the first room on the left (Acolyte position in Ikky 3). One Warden dropped Runed Glyph: Noxit and the other dropped Runed Glyph: Aexit. Aexit is used to open the next door on the right; Noxit is used to open the next door on the left.
The Warden cannot be slowed. I didn't notice them proc an FD, but won't say it couldn't have happened.