doctorhydrogen

I ran something pretty similar to this before crunching it down to a mono black deck headed by Drana. It's a lot of fun. Good to see you using Do or Die and Cover of Darkness, people never run those and they're both fantastic A couple of small suggestions:

Chaos Warp is about the only way you can deal with enchantments in R/B. Acquire one, because there's enough times when a Doubling Season or a No Mercy will run your day. I'd be tempted to run Recoup to recur it (or anything else) if needed, too.

I'd find a slot for Hero's Downfall over Doom Blade and friends, though if you're trying to save cash it'll probably be a dollar card come fall. I'd also consider Ashes to Ashes for one of those slots, as it will deal with indestructible Theros gods, Tajic, Avacyn, etc. and right now you have no way to handle those guys.

Black Sun's Zenith over Crux of Fate maybe? Again, you've got no way to deal with indestructibles, and nothing sucks than wiping the board and and leaving Sapling of Colfenor or Nylea staring back at you. Like Ashes to Ashes though that may be just me personally because I see a lot of those dudes in my meta.

If you can track one down and/or afford one Nirkana Revenent is a beast.

Blood Tribute can swing a game pretty wildly, though the CMC sucks.

Flamekin Villiage is pretty amazing in any deck that can run it.

Crackdown in mono-white can flat out ruin some people's board state.

Imo, Return to Dust > Disenchant. Yeah, it's a bit more to cast, but being able to hit Theros gods, Darksteel junk and get rid of the stuff so it can't be recurred via shenanigans is worth the mana. Plus you can choose to hit two targets.

Since money doesn't seem to be a worry Leyline of Anticipation is probably better than Ivory Mask in that slot, just by virtue of occasionally costing nothing to cast.

Looks super mean to play against. Good luck!

Infiltration Lens is a house in Odric, because the only thing better than saying "none of your eight dudes block" is saying "all eight of your dudes block my chump token wearing an Infiltration Lens, and I draw 16 cards."

IMO find a slot for Gift of Immortality. It lets you refling the same dude over and over, including one you may steal.

Good call on Smoke, I'm gonna find a slot for it in my Brion deck.

IMO the one extra mana you pay for Aetherize is worth either tucking the creatures or eating up their next few draw steps if they put them on top.

Glare of Subdual? You're going to have a lot of untapped dudes that you can use to lock down someone else's board before the end of turn.

How often is Talrand going to be tucked with that many counterspells, though? Proteus Staff is a bomb, but me personally I'd rather have Talrand be slightly harder to get if he gets tucked with the Staff if the trade-off is I can use Proteus Staff to get a Stormtide Leviathan or Jin-Gitaxis or whatever. I'm personally not a fan of Magus of the Future as he's so easy to remove, so I'm down with not running him, but I do think if you're running Proteus Staff it 's worth running a few other bomb dudes even if doing so makes it slightly harder to use it to save Talrand.

Just my opinion.

Cover of Darkness naming vampires would be solid here.

If you want life gain, Exquisite Blood will gain a lot more than Dragon's Blood and Demon's Horn combined will. It infinite combos with Sanguine Bond, too, though I intentionally avoid doing that in my deck just because it's kind of a lame way to win IMO.

Find a slot for Chaos Warp. It deals with anything, but more specifically it is literally your only way in these colors to hit an enchantment. For that matter I'd consider Vandalblast, too. Being able to destroy every single artifact not yours for one 5-mana spell is AMAZING.

Future Sight will be your friend. Remember that when you cast the top card, you flip and reveal the next card. I've chain-casted half a dozen cards in a single turn off Future Sight alone. That's amazing draw.

Depending on how much of a jerk you want to be both Quicksilver Fountain and Back to Basics will wreck some people's land base without hurting you a bit.

Polymorph is great in Talrand, although you'd probably want to run at least one or two creature to use it. Let's say you throw in a Stormtide Leviathan. Polymorph becomes 3U to make a drake and turn another drake into a Stormtide Leviathan. That is fantastic.

Switcheroo makes a drake and let's you swap one of your drakes for the best creature on the board.

Mystic Speculation makes a drake for three mana, then lets you scry three, then goes back to your hand so you can do it all again next turn.

You seem to be building on a budget, so all suggestions will be under a dollar:

Aetherspouts costs one more mana than Aetherize, and it puts the creatures either on top or the bottom of the owner's library instead of their hand. It's well worth that one extra mana to either bury them on the bottom or deny them card draw for a couple of turns as they pull their creatures back off the top.

Counterspell is like a forty cent card and costs one less than Cancel to do the exact same thing. Dissolve costs exactly the same but it has a scry trigger stapled on. Dissipate costs exactly the same but it exiles the spell so they can't recur it somehow. I'd run any over Cancel.

Condemn has the same casting cost as Smite, doesn't require you to have a blocker to use, and buries the creature (especially good if it's a commander) on the bottom of the library where it's hard to get to.

Last, I'm not quite sure why Backlash is in here as it's not legal in Isperia and isn't castable. I'm guessing that's a mistake :)

Oh, and for the same casting cost as Oblivion Ring you can have Detention Sphere which hits everything with the same name. It honestly doesn't happen that often in EDH, but I have hit two Nyleas before or a whole mess of tokens with it. If it was a five dollar card I'd say it's not worth the change, but for the same cost as Oblivion Ring I'd rather run Detention Sphere as there's no downside (well, mana is slightly harder to cast) but once in awhile the upside is big.

For one more mana than Favorable Winds all your dudes would get +1/+1 with Glorious Anthem. IMO it's worth it to hit all your guys.

Since you're running so many fliers why not run Archetype of Imagination so nobody else can have any.

I had much better luck with Derevi when I switched to almost all vigilance flies so I could save all my tap/untap triggers for locking their stuff down. It let me throw Stasis into the mix too for a lock, and run other lock things like Meekstone and Static Orb too. I'm not saying that's necessarily the play for you, but IMO you're too unfocused, and you're running too many cards that look like they're their simply because everyone says they're "staples". Is Karmic Guide and Sun Titan a great combo? Sure, but IMO I'd much rather just draw lock pieces than I would a combo that often times just durdles. Is Solemn Simulacrum an absurd value engine in some setups? Yeah. I watched a friend blink it with Brago like six times last week. But outside of turns 1-4 I wouldn't want to see it in Derevi over an actual card I'd use to win the game.

Just my opinion. It's also worth noting that I already had an Edric deck, and playing Derevi like this just felt like playing a bad version of Edric, so my opinion might well be biased there.

Seedborn Muse and Nature's Will are great here, too.

Dismiss into Dream ends people, flat out.

Nice call on Grand Arbiter. I might have to find a slot for him. Anything to make people tap more lands that they can't untap later is a good thing.

Bear in mind some of those cards can lend to a pretty unfun play experience. Mono-blue is generally not fun to play against, but stuff like Back to Basics and the Fountain make it worse. My Talrand decks basically only sees play when against guys I think are dicks, because then I don't feel bad countering all their stuff and locking up their lands.

Since you've said "cheap" I'll keep my initial suggestions to inexpensive cards:

Quicksilver Fountain- This can flat out end games early if you play it and not has a response.

Future Sight- You can play the top card of your library, which sounds useful, but you need to realize that when you play that card you flip up the next card. I've chained 6+ cards in a single turn off it. That's fantastic value.

Mystic Speculation- It essentially reads 2U: make a drake, scry 3, bring Mystic Speculation back to your hand. It's great.

Switcheroo- Five mana to swap a drake for the best creature in play, and make another drake in the process.

Non-cheap options:

Back to Basics- Absolutely shuts down some decks and won't hurt you a bit.

Sapphire Medallion- Will save a lot of mana

With only 7 non-permanent cards in your deck Primal Surge could easily put 20+ permanents into play. It's a straight-up win-the-game card in this deck.

Since you have no fliers I'd find room for Gravity Well or Gravity Sphere.

I'd replace a handful of lands with ramp. Skyshroud Claim, Cultivate, Kodama's Reach, Nature's Lore, Rampant Growth and Ranger's Path are all excellent, and you could easily pull six lands and slot those in. 47 lands you're gonna be topdecking too many. 40 is plenty imo.

If you're looking for lifegain options then there are lots better than Staff of the Death Magus. Grim Feast can get you 50+ per board wipe (it's errated to ALL opponents) and it's a fifty cent card. Whip of Erebos and Exquisite Blood both are a bit more but will net you a lot more too.

Triangle of War is another repeatable way to kill stuff with Glissa.

Since you're milling anyway here's what I'd add:

Swap Cancel for Hinder or Spell Crumple. Same CMC and they can tuck commanders making them really hard to get back out.

Run Spin into Myth as another way to get rid of troublesome commanders for good.

Since you're tucking dudes with Hinder or Spell Crumple or Spin into Myth, run Tunnel Vision. Tuck their commander (or whatever) then tunnel vision for it, milling their entire library.

Proteus Staff can be used to turn one of your drakes into one of your much more awesome creatures. Polymorph does the same, and it makes a new drake to replace the old one to boot.

Future Sight is way OP in Talrand. You can cast the top card over and over. I've cast a dozen cards in a single turn before off it. It's insane. That said, I'm running a lot more cantrips and mana doublers (Extraplanar Lens, Caged Sun, Gauntlet of Power) so I can chain cast easier than you, but IMO it's still worth it.

Wheel of Sun and Moon is great in Sisay, let's you shuffle the graveyard back to where it can be tutored again