UDK doesn't do anything in this team - like so often in arena. If he is not paired with champs that benefit from his passive, UDK is a wasted team spot. Threads where complainers say they can't beat UDK in Bronze arena don't change this.

UDK + Mithrala is a great combo. Add Duchess and the team becomes nasty. Duchess for revive and damage mitigation vs. AoE attacks. UDK protects vs. single target atatcks, Duches vs. AoE.