Ok so I am hatching my Regular Unicorn with a Fog Unicorn hoping to get a Grove Unicorn. What would the chance of me getting it be? I dont want to waste 17k gold for a regular unicorn. :(
Before I say the answer. 17k gold?!?!?! super cheap.
But to answer your question anything mixed with a promo pet (FOG unicorn is promo) will result in the promo pet's hybrid form 100% of the time for both people.