Help me level up my character in a MTG universe. Context : I am playing a lvl3 Fallen aasimar oathbreaker. He became one when he was tricked by phenax (mtg), god of deceit who was pretending to be tassa (god of the sea).  
  
Now he kinda embraces it and want to become a phenax cleric. What domain or god would be best fitting for such a thing? Note that i am open to looking at homebrews if needed.  
   
I have another question : at what level should i multiclasse or should i had? 2? 3? 5?