Tenacity

A character's Tenacity is a measure of how many magical effects he can hold onto at any given time.

It is equal to 1/2 Willpower * 1/2 Capacity.

Most spells change something about the world and then are quit. Some of these effects are instant (lighting a fire); some of them change something and then the effects linger, eventually wearing away (toughening armor). Occasionally a spell requires the caster to be constantly attending to it. These spells require Tenacity.

The Tenacity required by a spell is determined by the Capacity spent to cast it - half the capacity cost (rounded up) is the Tenacity required to be reserved to maintain the spell. For most casters this means the cap of any single effect is 3, for meeting the DC exactly and spending 5 capacity, but Sorcerers, with their 50% chance of semi-effectiveness even for "failed" spells, may occasionally choose to maintain a twisted spell, which will usually have an even higher cost.

Tenacity is not spent, it is reserved. If you reserve more points than you have Tenacity, you may either spend the difference in Capacity each round (a steep cost), or you must drop effects until your reserved points are no longer higher than your Tenacity.