Yes, that 's the way to make the script working when they respawn but they do every 1 second. I checked that code before, it's that because i said about "self:spawnMobiles". They respawn without the command but it breaks the script. Then if you use "self:spawnMobile" they respawn instantly but the script works. Btw, respawning instanly is not a good idea, especially if the npc is a high level.
And using this command will respawn twice and more times, when they respawn by timer and the instant respawn.
And i see your script will spawn a "giant_wampa1" and a "hth_wampa" every 100 seconds if they die. That makes 2 npcs one near other with different time triggers. When they die they'll spawn.
That didn't work for me. The script needs an only spawn by time but being a Observer.