Level 1 is cake if you have good cards; even as a tech quest you can 1-shot every level if you have a strong ATK team.
Level 2 has the enemies with some health, so they can get their skills in. They do have ice seal, so a full water team may be cut ineffective for 3 rounds if you went mono-elemental. The boss doesn't seem to be able to heal, but has some interesting abilities.
Level 3 has a jump in difficulty, but not ridiculous. You'll see some harder type of enemies this time around. There's also some Erinyes that can fully heal themselves, so time your attack skills properly. Your own Erinyes would be great here too.
Top level did require me to have some massive damage reductions. You can see I have both Alice and (Ocean) Banshee as follower/ally. Even then, stage 5 and 9 are the hard stages - they feature non-fire enemies to contend with.
You can see the new Ifrit and Agloolik here. Both of them have quick combo and seal abilities. Seal is annoying, but quick combo can eat a lot of HP off of you. Need to kill one as fast as you can - use skills as needed. The Thor can turn your fire diamonds to stone and do a full recovery one time. Takes a while, and does ok damage.
Here's the boss. Skills are as follows:
Dark Rules - turns all your diamonds black so you don't know what they are. Except that hearts are the rounds ones :P However if you move them around they will reveal them. So quickly move all the diamonds around to fix this.
Death Strike - a more powerful normal attack.
Melting Ice - turns your ice diamonds to stone.
Tons of Ifrit cards to get. Good for leveling the new Ifrit and Agloolik skill.
The boss card is pretty powerful, but for 60 energy, that's asking for a lot. The skill is "Fire Breath" which does 25000 flat fire damage. Only a 9 turn cooldown though. Leader skill doubles damage when you do a 3x combo or more, which is pretty easy to accomplish.
The goblin card seems to be an exp card. Dunno if you can evolve it like the owls.
Ifrit and Agloolik have the same skill as the unevolved versions, but have the leader skill of increasing ATK of your attack cards by another 50%.