Already doing all of those. I've had a couple of missions fail and I don't know why

Have you allocated the points in the proficiency tree yet? If not i would recommend doing that. The best elements i used for that dungeon was tank=earth, physical attacker=wind, and magical attacker(mage)=fire, but you can mess around a bit to see what elements fit you. Just remember for the points, focus on your pets main stats, tank=health (this looks like a heart in the proficiency tree) so make sure all points are in health, physical attacker=strength (looks like an arm) all points in strength, and for your magical attacker (mage)=intelligence (looks like a brain) all points in intelligence.


As for your failed missions, make sure you are sending the correct pet in for that mission. If the mission requires dexterity, then send a pet in with high dexterity. I also find that if the pet is higher in level than what the mission requires the better the chances are for a successful mission.