Manacosts

Many skills consume mana when used. The amount of mana needed for using a skill is determined by the variable and the basic mana costs of that skill. The variable costs are strongly connected to the rank of the skill. Therefore, other effects that raise the skill in dungeons must also be considered when calculating the momentary manacosts.

Mana requirement for a skill is calculated as followed:

(90% of basic mana costs) + (10% of basic mana costs for each skill rank over 1)

Example:

The basic mana costs for the skill Preventive Healing amounts to 7 Manapoints.
Your momentary level (including all increases) is 12 (which comes down to 11 ranks over 1).

Fixed part of manacosts:
90% of basic mana costs --> 90% of 7 --> 6,3

Variable part of manacosts:
10% * 11 * basic mana costs --> 110% * 7 --> 7,7

Total manacosts:
6,3 + 7,7 = 14

So using the skill requires 14 Manapoints.