It was Hard. I think it was in the eighty's, 70s maybe. 78 or 88, something like that. I could get to the end but then could not kill Siphi before everything went to crap as that wave also has double freezy dwarf. The first two waves are no joke either.
Since I dont have what it would take to stun everyone forever I thought instead I would Use Bystophus, (who i usually use) into Basher and just perma lock them out of their abilities.
My hard team saw a lot of iterations while I tried to beat it. But a normal version would be
UDK, Elva, Seer, Bystophys, Pythion.
Those levels with Siphis and Tormins can be a real pain.
In the past, I have used Shamael to insta-kill any desired enemy for some tricky levels. It might work for you, depending on who else you have on your team. You'd probably need attack up and defence down as a minimum requirement though.
Edit - I've also found Geomancers passive useful for Tormin too.
I took basher to 60 quite early on for my account. He doesnt have great gear, so I may not be the best to rate him, but I dont recommend him.
If your team is fast enough (specifically Pythion), you could try Arbiter, Pythion, UDK and either both Shamael and Geomancer, or one of them and one other guy.
Basically the aim is to keep your team alive while Shamael picks off the enemies one by one, or get Geomancers HP burn on the annoying enemies and let the opposite team do the work for you.
You just need to make sure you get block debuffs on before you start using any other buffs or TM boosts.
If you come up against multiple Siphis, then you'll probably need some CC and some RNG luck too, until you get some more champs.