To hit target
THT means "To Hit Target" and is used in Voln fu MB calculations. THT is similar to the 100 enroll needed to successfully connect with a melee hit or a warding spell. In these terms, then, one can say that the THT of any melee attack or warding spell is 100.
To succeed in a Voln fu attack, one's outcome must be greater than or equal to the THT value. Because the THT value is variable, one can view it as comprising the hidden AvD of a Voln fu attack. For example, a THT value against a one enemy might be 55, whereas the THT value against a better-armored opponent might be 85 -- here, the former attack (in terms of the usual 100 endroll) could be said to have an AvD of +45, whereas the latter has only an AvD of +15.
Finally, some other factors influence THT. Spells such as Spirit Barrier increase the THT, handicapping the Voln Fu user.