Absolutely agree with Reno_eNVy on this, don't screw up the whole batch by adding straight wasabi in the wrong proportions to the secondary. Try varying amounts of the tincture in a small measured sample of the beer to see which proportion works best. And if you happen to have some existing IPA (even commercial examples), just try a little wasabi paste mixed in to see if it's worth pursuing. I made a wasabi strong ale last year that was way hard to choke down, but it was mostly just an awkward blend of flavors, an IPA would probably hold up a little better against the wasabi profile.
Good luck