Your weapon temporarily becomes your hands, and your hands shoot explosive fire bullets. Finger Guns replaces your equipped weapon for a while with explosive fire bullets. It is the only spell that completely changes how you play for a few seconds.
Strategy
Use it as a burst window against bosses or elite enemies where you need maximum damage in a short time. Pre-cast Wisp or Fireball to have Burning targets ready for the explosive shots to interact with.
Strengths
Explosive fire bullets for the duration
Pairs with Burning targets from Wisp or Fireball
Weaknesses
Disarms your normal weapon for the full duration
Very long cooldown - the burst window doesn't come around often