The Giant Mole Is a popular boss for people to grind for the Mole Pet Drop. Taking almost no damage, it's incredibly easy to kill. The only downside is currently the Giant Mole is in a singles area. If it becomes a multi area, You SHOULD be able to use your familiar to find where the Mole digs to when its Health is low.
The only real mechanics the giant mole has is basic melee attacks you can mostly ignore. When he is 50% HP or lower, he will dig to a random part of the cave and you will have to find him. A good way of killing him is to use a poison / venom weapon so while it takes you a bit to find him he is continuing to die (Poison damage won't trigger him to dig again) Like stated above, If the cave is made into a multi combat area, You should be able to use your familiar to find him when he digs as he will walk to where the direction of the mole has gone.
Bring your best melee gear and a stamina potion or 10. Realistically Mole is weak to almost everything, So Mage / Melee it in whatever you want to use.