Apparently tenacity/foresight up negates drain force.

"Vertigo;928224" wrote:
Foresight stops it, as in the whole attack is dodged (just like when B2 or Ventress's dispel is evaded), but it goes through tenacity up.

Are you sure? Every video I've seen of it fails to display "Cooldown Increased" when the target has Tenacity Up, and there have been too many characters that have had Tenacity Up that haven't had it applied for it to have just missed the 50% proc chance every single time. Something like a 50% ^ 11 = 0.05% chance (1/2048). So while it is irresistible normally, Tenacity Up does seem to stop it.