Presumably he doesn't have an inherent Force-based defence as an energy vampire drained him and I believe he wasn't able to defend against the Dark Reaper. So unless Anakin taught him Ulic's technique afterwards, he probably can't actively defend against it.
On the other hand, he does have Vaapad, which could reciprocate/reflect a pretty disparate range of powers both tangible and intangible. Drain's a considerably more arcane power than augmentation and Lightning, but not necessarily in a way that makes it exempt from Vaapad's properties. And since Mace's limit was RotS Palpatine, there's no way Valkorion is just overpowering his Vaapad or anything.
Drain's a direct siphon of one's life energy, not a Force attack. Vaapad isn't a one size fits all ace card.
Not that it matters, Valk's demonstrated multiple means of overwhelming Force users entirely.
More importantly, Mace's vaapad doesn't actually encompass stalemating Sidious. It's directly stated that Sheev's lightning was beyond his superconducting loop.
Originally posted by Beniboybling
Personally, I'd like to see what arguments people have for Windu's defense against Force drain, should Valk choose to use it.
Easy. Windu powers through it. Valk's drain is garbage. The devastation of Ziost was a ritual and when he possessed the populace, he couldn't even drain their life energy directly and instead had to kill them first to feed off of their death. The only times he's directly fed off of another being is through a preestablished ritualistic link with another Force user e.g. Revan.
Windu slices him up 👆
Originally posted by AzrongerMmm, and with Windu siphoning Valkorion's power, it's even less likely to be effective. mmm
Easy. Windu powers through it. Valk's drain is garbage. The devastation of Ziost was a ritual and when he possessed the populace, he couldn't even drain their life energy directly and instead had to kill them first to feed off of their death. The only times he's directly fed off of another being is through a preestablished ritualistic link with another Force user e.g. Revan.Windu slices him up 👆
This is a good point. 👆