Summon the Unicorn

From: Isabelle
Description: We have all the horns. Now we can perform the ritual to summon the Unicorn. You arrange the horns while I start reading the spell.
Completed: Amazing! As soon as I pronounched the last word, a star lit up above the circle of horns! I could hear a neigh and see the dim outline of a snow-white unicorn. But suddenly the fog is shrounding everything... Oh, no! When the fog dissipated, only the Unicorn's horn remained in the circle - and nothing to lead us to the answer we need.