How I did it was:
I had 2 FA, 2 LSA, Boost Aura, SandTrap (Destructive Pylon) Box shape Reflect Beam with Shattering Torpedo and Poison Protons. This was my defence on each lanes (Spawn) with a SGT for the air units that sneak pass.
My CC was relying on the RB & Proton petrify combo with slow from the SandTrap. For the bosses I had to play as the Gun Witch with FrostFire, full AP, I find her efficient to take out the siege roller. Assassins are always going to kill you no matter what, Pre-cleanse by changing the colours to one colour, you may get lucky.
FA: Destruction (G), Defence Rate (G), Deadly Strikes (G): Anti Orc, Anti Melee, Defence Range
LSA: Mass Destruction (G), Destruction (G), Defence Rate (G): Anti Mini, Anti Range, Anti Melee
Boost A: Destruction (G), Boosted Power (G), Deadly Strikes (G): Diverse Power & Crit, Power
SandTrap: Destructive Pylon, Vampiric (G), Deadly Strikes (G): Diverse Power & Crit, Defence Rate
RB: Destruction, Shattering Torpedo (G), Vicious Strikes: Anti Melee, Defence Rate, Tenacity
Proton: Defence Rate (G), Destruction (G), Frosty Beams (G): Poison, Controller, Tenacity