Call them Wrathers.
You could divide Wrathers into three classes too :
Warrior Wrather - rams into you and attacks at close range dealing some damage,but have no skills or magic.
Mage Wrather - they can shoot either fireballs/ice spikes/shock waves at you,and depending on your equipment,they can either do more or less damage to you.Some fireballs can burn your character and slowly take away their health,some ice spikes can freeze your character for a certain period of time,and some shock waves can paralyze you for a short amount of time.
Giant Wrather - they have a wide radius of attack,being able to attack players from all sides at once with a powerful quake,and they also have to ability to "hold" nearby players,rendering them vulnerable to the next attack they receive.
Also,some ideas for equipment :
Giantproof Armor - Giant enemies won't be able to hold you.
Robe of Resistance - Magic attacks deal 50% less damage to you,but physical attacks deal 35% more damage.
Sneaking Mantle - Attacking an enemy from behind will deal 40% more damage than usual.
Parrying Shield - when attacked by physical attacks,your character has a 5% chance of taking no damage at all from that attack.
Soul Steal Ring - when you kill an enemy,you regain more MP than usual.
Sturdy Coat - physical attacks deal 15% less damage to you.
Experience Collar - You receive 10% more Experience when you kill an enemy.
Also,some suggestions for new and different enemies :
Jumper - These guys can latch to you and slowly drain your HP.However,they are very fragile.
Bomber - These guys run like crazy,and after receiving the final blow,after a few seconds,they explode,dealing damage to nearby enemies and allies.
Big Jam - These giant zombies like to puke acid,and they need a lot of hits before dying.Their puke sticks to the ground,and deals damage to anyone who steps on it.
Laser Alien - when their laser hits a wall,or a living being,they do radius damage around the area they hit.
Boss : Major Wrather - He can summon other Wrathers at will,and they can do insane amounts of damage with their "X-Claw" attack,which hits in four different directions.They can also "hold" your character,leaving them vulnerable to the next attack they receive.
This is all i have to say.Good luck with your project!