You can get two Fire Unicorns during the current event — one from the Instruction, and another for clearing 70% of the Witch’s Lane.

   
You’ll need Mystical Fire to build your unicorns. In Witch’s Lane, you can collect 720 units of Mystical Fire, which is enough to build one full unicorn and half of the second one.

Another Fire Unicorn, along with more Mystical Fire, will become available in next week’s Halloween-themed temporary location.