Gazelle for Wu is what I did.
Remember that her special removes all buffs too so keep that in mind when choosing your team.
Ideally you want heroes that effect the titan more than your own heroes. Mist is a good choice as she slows the titans mana and also makes it more vulnerable to your other heroes specials.
Jackal a great pick for defense down. Poseidon is a great sniper and would be amazing fired after Jackal and Mist.
Keep Viv on as the healer.
Guillianbursti I’m not sure of, never used or fought him but looking at his special I’m not sure how he would mix with Gazelles special. I don’t know if the health boost would activate while your heroes are dancing but I know the attack boost wouln’t activate (but Gazelles is better anyway at base level). He may be worth keeping on the team IF his health boost part of his special works while dancing. it’d actually be an amazing combo but someone else will have to tell you if the specials are compatible or if Gazelle cancels it out