When you have the 2 piece PvP set whenever your non lethal applies so does crippling, so there’s no point in applying that manually. Mind-numbing is what you want here.
Lethal poison depends on the target. In a BG I always use Wound poison, as it helps negate enemy heals a bit. But in Arena, it depends on the team. If there’s no healer I use Deadly poison, but always wound when there’s heals flying around…
Happysap sum’s it up well. I used to use wound poison back in WOTLK when it gave the crippling debuff too (as mut/ prep spec), but have so far ignored it for deadly for the sheer dps output which, works on all units not just those being healed.
I’d like to see some stats on how effective wound poision is though.