I’ve seen scylla with full HP and with less than 100 str (but with two big guns). Buts scylla with crashers and armored legs had 147 str (exactly which i captured)
If you have a biochimist assault you can put 12 virus damage per turn on a scylla. Every virus damage above half of his max will is a turn of panick. I nearly capture my first scyla. But my assaul have done an insane amount of damage with a laser rifle (even with the insane armor on the scylla). The scylla dyied of blood loss when I needed one hit to paralyse it.
Or 2 assaults to paralyze her in 2 turns. 