A Banewolf chem cannon plus heavy flamer: against any unit with a 4+ or worse save, this is an awesome combo.
Against marines, it doesn’t work.
Example: Say your templates can each hit six marines in a six marine squad. The chem cannon gets 5 wounds (unsaveable) and the heavy flamer gets 4 wounds (saveable on a 3+). You think you would kill at least five and probably all 6 of the marines, right?
Here’s how the marine player could tweak wound allocation:
Marine 1 / Sergeant: 1 heavy flamer wound
Marine 2 / Meltagun: 1 heavy flamer wound
Marine 3 / Missile Launcher: 1 heavy flamer wound
Marine 4 / Bolter: 1 heavy flamer wound, 1 chem cannon wound
Marine 5 / Bolter: 2 chem cannon wounds
Marine 6 / Bolter: 2 chem cannon wounds
This leaves 3 dead marines with bolters, and three specialists that only have to take one 3+ save.
Wound allocation is funky. Don’t get me started on Nob squads tweaked for maximum allocation abuse.