Hero suggestion

Amon, Hybrid form(from The Host in LOTV Campaign)

Dr. Narud, Scientist form. His ult abilities make him transform into target enemy hero(anti-thesis of Abathur) or xel'naga form.

Gabriel Toshi, Spector. His strong point is siege stratege with a nuke. (like in WOL Campaign)

Selendis, replacing Qhira. ( https://www.pinterest.co.kr/pin/548102217133562031/ )

Talandar, Praetor form(in LOTV). His legendary skin is a zealot Fenix(in SC 1). One of his ults is transformation into an Immortal or Orisa.