Use Emperor Thaurissan while having 2x Mind Blast, Prophet Velen and 1x Mirage Caller in your hand.
This will allow for an easy 40dmg combo by using Mirage Caller on Prophet Velen.

If you need more damage because of armor, try discovering more Holy Smite or Mind Blast with Shadow Visions .

You can Mirage Caller an Emperor Thaurissan while having multiple Mind Blast too. Or save a coin from Gilded Gargoyle.