Ok,
1 after EVENT ANY DAMAGE use a BRANCH connect false to ADD IMPULSE.
2 Create a variable (bool) name it Invincible (default unchecked) Use it to switch the branch.
3 after SET HEALTH, SET INVINCIBLE to true (checked)
4 after you’re health =0 BRANCH (FALSE) use a DELAY set it to 3 sec
5 after DELAY, SET INVINCIBLE to false (unchecked)