I'm VR16, and have only played one group dungeon. (Fungal Grotto) I just beat it about an hour ago, and outside of one mini-boss it wasn't that hard. However, I've heard that Fungal Grotto is by far the easiest group dungeon, so I'm curious what others would be possible considering my build.
I use a Magicka Templar, with 30K Magicka, 20K Health, 1400 Magicka Regen, around 1500 Spell Damage, and 53% Spell Critical. My offensive skills are Puncturing Strike, Toppling Charge, and Radiant Glory. My defensive skills are Harness Magicka and Restoring Focus, while I use Honor the Dead to heal and Inner Light as well.
From what I saw in Fungal Grotto, my biggest issue comes from mobs who kill me faster than I can regain health either from Honor the Dead, or while attacking with Puncturing Strike or Radiant Glory. I had no issues running out of Magicka, and even though I have extremely low Stamina I didn't find that to be an issue either.