Looks like I spoke to soon. While the bot doesn't randomly stop attacking with the id i mentioned, it still doesn't use mangle properly. I'm using this now as a fix for the op's custom class (should work for all languages).
if IsSpellKnown(33917) and IsSpellReady(33917) then
_Log("Cast Mangle");
LuaDoString('local spell=GetSpellInfo(33917); RunMacroText("/cast " .. spell .. "")');
NextAction();
end