Try this custom bouqet:
Code:
AzNWAQAuVNtUzVSS2UrqNol2KnZTGKSinyQMg9+kfFOK4UpwUKp0SapyTHScJAtRaqkSLVap5SgOk2oVpWUSnkvEeYlqqqTTFE2XclGFXlFdFnonlboqkbZKFZulou1SyUel6qtU+CxVNQ8ljVRK45TKaJJ6rIKTEmWaSq6hxD3iuuCvEnqKTLcWVCG2nsiUmJoh854cAGhhrZdHZnRlFHov69IZU6dbC6oQ2+jKKJQbLzXMdrKeF/pOddTXTU23FlQhNqnFtfNJqcUFJ2sIZeHbY++qbhfZx5Wig6xakuxBaiaLU93LvCcHAGLLvIMDAFW2zHtyAKC9zDs4AFBdyrwnBwCqCpn35ABAS5l38N0/yDZJsrckKWTekwMAWU2SrFKSrCnzXnAAIBukPotPymz8AgcA6gzGoZmaIZSFM7EFxjgbE2I32X6Z9+QAQJaReU8OAA==
You can then assign that to an indicator or HoT Icon and it will only trigger when the unit is below 40% health.