There are many ways to clear this dungeon level. I’m sharing the method I used.
My method is for non boosted players, I cleared when the guardians were not released so I did have some tough time clearing this level.
Spells should be maxed and forged well plus gear like omega belt and blizzard items atleast 2 is essential plus heal ring.
Troops - Monks, Froster, Pyromancer/Arblasters
Spells - Blizzard (range to hit the gargoyle tower, I think 6.49 or may be more), Firestorm and Swordrain (Stun helps, plus range to hit a lot of troops)
Pal - Kaiser, if Fritz is used you will need Sonic Blast or HammerStrike
Guardian - Trusty (as its available it will make things easier)
This zone 1 is where the gargoyle tower that kills the troops summoned from tent plus the bomb towers at the extreme left. So in order to have a stead flow of troops the gargoyle tower needs to be taken down. I spent atleast 3 blizzard to take that gargoyle tower, I will hit the blizzard and then move forward and clear the towers at zone 2, when blizzard is recharged I return and hit the gargoyle tower and run forward till the spell recharges till the gargoyle towers are done. Monks are used to heal the king, and frosters are used to slow troops in the opposite lane (frosters are used to reduce the primal howls health before you engage them, so can arblasters).
Once the gargoyle towers are taken down I move forward to zone 3 and take down the heal towers (both at the opposite lane and the one on the lane) using sword rain and at the same time firestorming the firebolt and frost towers meanwhile kaiser destroys the snake tower and spikes and anything in its range to its potential.
Zone 4,The turn is where you have to have firestorm and swordrain charged so you reach the turn hit the sword rain stunning the towers while firestorming them while kaiser uses the sonic blast. This way the corner is cleared reaching the siege point. The howl beast is released from the castle make sure you have blizzard prepared and it will take 2 blizzards and may be one more if your frosters/arblasters havnt engaged cross lane, If you have low time just ignore the beast but be quick and you can move forward to clear the rest of the towers and blockades and reach the castle gate kaiser helps you with clearing the towers, but make sure its level 8.
This is not the best method but its possible and I have fought this dungeon many times with this method.
If you use trusty you can save a lot of time and do a lot of damage to the first gargoyle tower, so a trusty activation + one blizzard might be good to take down the gargoyle tower and the second activation save it for the howl beast. If you use fritz it would help you with howl make sure you have sonic blast or hammer strike to take down the towers, but you wont be able to finish the gargoyle tower at the start so gathering troops and calling forward by scream can help plus some insta troops. Boosted troops will help a lot, but can be done without them too.
You can come up with your own combination. Its been a while since I’ve played so might have forgotten many things. This level was frustrating and tough for me though lol.