Warden will be just fine for that. I am coming at this from where you might solo world bosses or compensate for weak players in dungeons, e.g. where you are fairly self-sufficient. In terms of skills, look for:

Spammable single target ability, choose one of these:

• Force Pulse or Crushing Shock. Benefit: Procs weapon enchant, magicka return from destro passive on kill.
• Screaming Cliff Racer. Benefit: Heals you while attacking.
• Elemental Weapon. Benefit: Cheaper and probably highest sustained damage.

AOE and damage over time abilities, choose at least three of these:

• Winter's Revenge
• Elemental Blockade
• Deep Fissure: Warden signature skill, hits hard and debuffs enemies for increased damage with other skills
• Growing Swarm

Defensive and healing skills. Choose at least the first two:

• Living Trellis. Superb survivability skill that doubles as a decent on-demand heal.
• Ice Fortress. Your standard defensive buff, the warden version includes Minor Protection. Very good.
• Shimmering Shield. When dealing with lots of ranged attacks.
• Mutagen or Rapid Regeneration.

Buff and sustain skills. Choose at least one of the first two:

• Betty Netch.
• Elemental Drain for sustain, especially if not using Deep Fissure.
• Inner Light (esp. with Northern Storm also slotted) or Lotus Blossom.
• Bird of Prey. More passive damage and some running speed.

Offensive Ult: Northern Storm, Elemental Rage or Meteor. Choose one.
Defensive Ult: Northern Storm, Healing Thicket or Light's Champion. Choose one.

If you like the Warden bear, use / try that instead.

In terms of gear, choose 5x light armor, 1x medium, 1x heavy. You'll have to experiment a bit so you are just defensive enough not to die. Consider combinations of the following:

Monster sets:

• Valkyn Skoria (offensive, universally useful)
• Grothdarr (offensive, AOE)
• Zaan (most offensive single target)
• Blood Spawn (balanced utility set)
• Troll King (more healing, tanky)
• Pirate Skeleton (tanky, but on and off)
• 1x each from the following: Chudan, Pirate Skeleton, Lord Warden (tanky)
• 1x Domihaus + 1x other (just more stats can also be good)

Offensive sets:

• Julianos
• Spell Strategist
• Mother's Sorrow
• Amber Plasm or Shacklebreaker (some content may require break free or dodge rolling, useful for that)
• Necropotence (with netch and/or bear)

Sustain sets:

• Seducer
• Lich

Defensive sets:

• Fortified Brass

You can also compensate for any lack of defense by making Protective jewelry. Mundus should be Atronach or Apprentice.