Some Skills in Wyvern Rising can make a character tell the truth, some just allow the person using the Skill to know the truth. Some Skills allow you to lie even through the use of those other Skills. The rule is, if a Spell, Prayer, or Skill makes you answer the in-game question, it is Mind Altering, and therefore a Skill like Willpower can resist the effect. If the Spell, Prayer, or Skill doesn’t make you answer an in-game question asked, you need a Skill such as Silver Tongue to be able to lie in this situation.
To avoid situations that could lead to meta gaming, you may tell the lie, and find a Rules Marshal, Staff Member, or Director as soon as possible to let them know you used a Skill, Spell, or Prayer to do so and it has been expended.