Because you mentioned card advantage, have you considered the following?

Smuggler's Share:Anytime an opponent draws an extra card is often. Plus, the random treasure every now and then.

Well of Lost Dreams: You have Dawn of Hope and the well is similiar but has a much higher ceiling. Big beater and mana open can easily net 4+ cards.

Court of Grace: On theme and keeping the monarch is easier with a bunch of fliers. Will at least replace itself and give evasive chump blockers.

An unrelated card to card advantage would also be Reconnaissance. It's purely for combat but allows you to swing with impunity with every creature every turn. Unfavorable block? Untap and back out. It also grants pseudo vigilance since you can untap and remove from combat after damage with zero downside.

Like the deck. Honestly looks good as is but alas, we are never finished tinkering.

This was enjoyable. I wish I could buy it.

Fire and Ice is the best. The added evasion can also help it to get through (pro red being a bonus against the other flying heavy tribe, dragons). The Shock in commander doesn't always help a bunch but there are plenty of utility creatures to Murder.

Infiltration lens is terrible unless you have a slew of ways to force them to block.

The other two are solid budget options.

Edit: Mask of Memory is better than the gloves. White does have recursion but even without, the mask let's you sculpt your hand much more efficiently. Pitching a land in hand you don't need to draw two is better than just draw one. Plus, it uses less mana.

I probably have too many planewalkers. Goldfishing, I tend to get mana flooded more often than screwed, but I will consider cutting a ramp piece or two for lands.

I recently cut Ashnod's alter because I didn't need a ton of colorless mana but Phyrexian could help. At this point though, just going to cut three more cards to finish before any additions of tweaking. I cut most of the aristocrat suit already but I may rebuild if it doesn't run how I want it to.

Thanks for the comment. It does help, especially if I tweak post completion.

Thinking of defense, Ophiomancer could work. It triggers every upkeep, so you should always have a 1/1 death touch blocker. I've found small death touchers tend to give outweighed influence when people determine attackers.

Though, it doesn't directly move your game plan forward. It's about as useful as a Propaganda or Koskun Falls.

How many times has Diabolic Revelation netted you 3+ cards? Did you win the same or next turn? How many times has it been a dead card or only netted 1 or 2 cards?

7 mana is also a lot for a tutor. Does your deck have decent recursion? Can you play Entomb then Reanimate?

In a vacuum, I'd go with the demon but personally I'd play a mana rock or some synergy piece over expensive tutors.