With so many X spells, were going to want to use mana-doubling permanents such as Dictate of Karametra or Mana Reflection
The cards Ragavan finds will typically be harder to cast in early turns, making the card advantage version of Ragavan iffy
At 4 mana, its going to be an integral part of your deck, often coming down on turns 3-4, and it provides a lot of value
The Blue Spirit gets over the hump as a flash enabler for your first creature each turn
Who cares about throwing away a few tokens when you surgically remove the best permanents in play, netting a death trigger or three in the process
Your rats wont poison opponents without Karumonix on the field, so sticking it to the field early is essential to making this deck run