5th slot on arena squad

So I'll be unlocking traya here in about 2 weeks and I'm already hoarding her gear and zetas. So I was looking to run traya lead with sion and nihlus and thrawn but was debating on my 5th slot. I thought of sith trooper but there's characters in the meta that can bypass taunt. I already have nest at g11 and I even thought of palpatine for his crackling doom since there's so many jedi in arena these days and I already have him at g12 with his unique zeta. I'm even open to other suggestions