Leopard Fang Flaming Palm: Essentially a powerful fire punch.
(At least in the beginning): He regards Rimuru as a "lowly slime" who couldn't possibly rule over all of the monsters of Tempest and couldn't possibly rule over (at the time) 30% of the Jura Forest. He thinks Rimuru is a weakling and a phony.
He is scared of her and what she is capable of. Phobio is only a minion of Karion and he knows that Milim is one of the most powerful Demon Lords, surpassing even his master, therefore far surpassing him as only a minion. Even the sight of her makes him uneasy. He does swear to take revenge on her one day, however.