Traditionally it’s always bad when a forbidden ritual goes awry at the last minute. At least for the bad guy who almost always dies a horrible death.
Knowing this you would think the villains would practice those rituals till they knew them backwards and forwards and couldn’t be distracted at the all too critical moment.
I mean just the other day I was summoning an elder God from beyond time and space, you know, just a typical Saturday night when some do gooders broke into my secret mountain fortress and tried to save the world. Well long story short they’re dead now and the whole entire world will shortly be devoured by an angry elder god.
Andy why? Because I was prepared.