my bad, fixed it to work with poison and shell
*.refshell *.refpoison add sgn -1 add 5 mult -1 add .shoot store
What he ment was that -6 shots won't trigger poison and -1 shots are more powerfull against shell.
As far as I understand (not sure or anything) then a -1 shot will trigger poison if the target has more poison than shell.
So if you don't want to get poisoned but still wan't to use -1 shots against shell then only fire -1 shots if the target has 0 poison or less poison than shell.
But beware some bots create more poison if they get hit by a -1 shot... so often the safest solution is just to stick to -6 shots unless you're in the F3 league (no poison or shell) or maybe when eating alge.
To get more from an alge you could switch between -1 and -6 shots.
.dnalen .memloc store
*.memval 13 = 'Alge dnalen is 13
-1 5 *.timer 2 mod mult sub .shoot store