Making boss phases

How do i make it so my boss switches phases when he’s at a certain health?

Put all of your “phase 1” events under a event which only has a condition “BossHealthVariable > whatever health level you want”

Then do the same for phase 2 and another new parent event, but make it have a condition of “BossHealthVariable >= healthlevel you want” AND “BossHealthValue < The health level for phase 1”

Repeat as needed for each additional phase.