Leonin Arbiter is good, but you have at least five fetch lands where paying 1 life and then an additional to search for a land when you can play Rampant Growth for the same function doesn't make a lotta sense
With no other keywords or abilities, Mufasa, King of the Pride Lands is a very simple sapphire card: it has a formidable balance of both questing power and challenging prowess
While this would require your opponents to be drawing all the time, thankfully, thats hardly uncommon in Commander
You can pay three mana to give all of your creatures +1/+0 until the end of the turn, but the main ability is that Purphoros will deal two damage to each opponent every time a creature enters on your side of the battlefield
In exchange, however, you do get an awful lot of value
The card it reminds me of the most is Monastery Mentor, only having flash makes it more versatile