Immersa goes last in each round, so this is round 168 for her. Remember, if she steps back 5', she will be in the swirling dust.
Immersa hits with bite only for 7-5=2. PU2 has 22 HP left, and looks shocked that he was actually harmed.
Round 169: PU2 breathes at Immersa, who finally manages to stay conscious (rolled 20 Fort save). Go ahead.