Figuring out rares might be the hardest part of Limited Magic.
People ignore rares all the time in discussing Limited because they are, well, rare. Even in weeks of Pro Tour testing, it's common for someone to never open or play with a given rare. Despite this, rares really do matter. While you might go through all of Dominaria draft without opening Teferi, Hero of Dominaria, a reasonable amount of the time some rare is going to be the best card in your deck.
So, let's talk about rares using some of the ones from Core Set 2019. How should you plan your draft around the highest power cards in a set?
Rule 1: No rare is infallible.
A few years ago, Magic Online used to be set up in a way where people could gather tons of data about draft. Bots were set up to watch tens of thousands of games and crunch the numbers.
Elspeth, Sun's Champion was the absolute best Limited card in the set it was printed. It was the best Limited card in the block it was printed. It's among the ten best Limited cards printed in the last decade.
Elspeth only won 70% of the games it was cast in.
Elspeth wasn't cast in every game it was drawn. Decks with Elspeth didn't draw her every game.
No single rare can carry a draft by itself. The rest of your deck has to do something. If you draft a bunch of worse cards to support your rare, your deck probably isn't good.
Rule 2: Some rares don't need help
Tezzeret, Artifice Master looks like a card that makes you want to play artifacts. If you have more artifacts you draw more cards!
But it doesn't need that help.
If you just draw one card a turn off the +0 ability, you are probably winning the game with Tezzeret. That has been the case with every planeswalker that draws cards, and this one even starts with a ton of loyalty.
The artifacts in Core Set 2019 aren't bad cards, but they aren't great. All of them are worse than the non-colorless cards of the same cost. If you build a deck with a bunch of them you are drawing worse cards on average when you don't draw Tezzeret. You are drawing worse cards to protect your Tezzeret with.
Maybe if this changed your Tezzeret from OK to a game breaker this could be justified, but like I said this is a planeswalker that just does normal planeswalker things like winning games by itself.
Another card in Core Set 2019 that falls into this category is Resplendent Angel. It doesn't need to you play a bunch of life gain cards since it gains the life itself. In fact none of the life gain cards even trigger this by themselves, so you need to throw multiple cards down the drain when just paying mana and attacking works!
Rule 3: If a card rewards you for playing normal cards, it is good.
Sarkhan's Unsealing has a really powerful effect if you can support it. As evidenced by the common Electrify four mana for four damage is a fine rate, so if you can have Sarkhan's Unsealing trigger twice in a game it has more than worked out. If you ever get the seven power four to everything trigger it's just game over.
There's a lot of four power creatures in Core Set 2019 that are just fine to play, so for many red decks supporting Sarkhan's Unsealing is as easy as playing creatures. If you are playing green or black with your red spells it should be a given. A three mana 4/2 (Onakke Ogre) or a four mana 4/3 trample (Havoc Devils) or a five mana 5/4 (Fire Elemental) isn't anything you are clamoring to pick up, but you are going to fill your deck with these cards anyways. If it means preferring those to the similar 3/3 haste (Hostile Minotaur) for four you aren't losing much. You take Sarkhan's Unsealing first, then assuming you stay in red aim to draft green or black and pick up the bigger creatures in the middle of packs over smaller creatures in similar spots. You leave the draft with a mostly normal deck, but it has a Sarkhan's Unsealing that is absolutely insane
Starting the format, I'm very willing to first pick Sarkhan's Unsealing and aim to play six or so large creatures to trigger it. Maybe after I see the card a few times I realize something about my assumption was wrong, but up front it looks like I just have to play the right average cards to make it a slam dunk.
Rule 4: If a rare wants you to play bad cards, you need other payoffs too.
Let's hop back to artifacts for a second. Sai, Master Thopterist has a lot of potential. But, like we said earlier with Tezzeret, the artifacts in this set aren't great. If you don't draw your Sai to make everything hum along or if he dies, you are going to have a deck of bad cards. But if you have other cards in your deck that make you want to have the same artifacts that also upgrade them to really good cards, then you can have an on point deck for Sai.
A quick search of the set reveals a few things, but the common rewards are tiny. They don't full on upgrade your deck the way Sai does. The uncommons are good, but as uncommons that means you won't see them that often. It looks like a Sai, Master Thopterist deck might come together sometimes, but I'm not taking it early and trying to make it happen the same way I would with Sarkhan's Unsealing. The bad Sai decks are a bunch of bad cards with one good one. The good Sai decks require a lot of specific things to go right.
Of course, a 1/4 for three isn't that bad. If I incidentally pick up a Sai it might make my deck as a three cost creature. I might try to play extra artifacts as my last spell or two. And then I just have a fine card that upgrades a few of my other cards I would play anyways.
Death Baron is another card in the same category as Sai. The Zombies in this set aren't that good. There isn't another card that really want you to play Zombies besides Liliana, Untouched by Death, a mythic rare. If you play Death Baron and ten Zombies and draw your Zombies without Death Baron it isn’t great, so I won’t be trying to end up with a deck like that barring weird multiple Baron drafts. But if you get a bonus deathtouch creature in a game due to Death Baron that is great. Again, I'll choose to play a Walking Corpse as a filler two drop, a Skeleton Archer as my four drop, and Death Baron will be a way to make some of my already played average cards a bit better.
Rule 5: Long games reward great rares
Let's step back to Tezzeret, Artifice Master.
Tezzeret is possibly the most powerful Limited card in Core Set 2019. As I mentioned talking about best rares, there's some caveats. You have to draw and cast your insane rare for it to help you win the game.
This is where you can build around Tezzeret. You don't have to be a control deck for it, but it is better if you are one.
A deck with Tezzeret is going to want ways to see more cards. Divination and Omenspeaker are two great examples of this in Core Set 2019. They aren't better than good removal or other good finishers at making your slower deck good, but they are among the first other cards I want to play.
Assuming everything else pans out, I'm also going to be looking less at playing other weird plans. I have a Tezzeret and probably a Snapping Drake or two. What is my opponent going to do that I need to Aether Tunnel through? I'll find my planeswalker, make a bunch of Thopters, draw a bunch of cards, and eventually they will lose.
Rule 6: The scope of rares matters
What about Leonin Warleader? Can you build a control deck aiming to draw that card every game? A 4/4 that makes more attackers is certainly an absurdly powerful rare, but it isn't quite a Tezzeret.
If you draw your great rare on turn ten, odds are the battlefield is fairly stable. Not a lot of things are attacking or someone would have lost a while ago. The various creatures are hanging out, threatening to block. Leonin Warleader in this spot just attacks, gets blocked, and dies. That's it.
To build a deck aiming to draw your one rare to eventually win, you need a rare that wins these long game stalls. Any of the Elder Dragons qualifies here, except maybe Wall-theme weirdo Arcades, the Strategist.
Scope also comes across in terms of available answers. If you draw Djinn of Wishes late in a game it is probably killing your opponent, but they could have just sat on a removal spell for a bunch of turns without anything to use it on. You might need a backup win condition if your best way to win is Djinn of Wishes. Planeswalkers are really hard to kill on stable battlefield though, and something like Chromium, the Mutable is just not going to die ever, and as a result you need less Snapping Drakes to help close out in decks with those cards. I'm still hoping to open Djinn, but I am building my deck with several other ways to win the game.
Rule 7: …. But scope isn't static
Let's talk about another great rare: Pelakka Wurm. A 7/7 trample that gains life and gets you a card when it dies is great, but in the late game stalls I described it might not be a direct end to the game. Your opponent can put two 4/4s in front of it. They end up down a card on the exchange, or maybe multiples if they just had a 3/3 and a 4/4, but your Wurm is dead and the near term threat is gone.
If you have some way to hit them with the Wurm again, they have to fight the same losing battle. Maybe this time they have to lose a bunch of 2/2s to kill it in combat and your Wurm breaks their defenses for your other creatures. Or even better, you just Wurm them again and this time they just die to it.
You obviously have to apply these cards sparingly as Macabre Waltz doesn't do quite as much until you draw your Pelakka Wurm, but this is a way to make a sure game winner out of a rare that might just get you card advantage without killing your opponent.
A Few More Examples
Let's look at a couple more examples to close out.
Ajani, Adversary of Tyrants is a planeswalker that doesn't have weird restrictions, so it has to be good, but where does it fit in this discussion?
Well, returning a two drop creature to the battlefield is ok but not a big impact. It costs too much loyalty to do multiple times, and most of the time is just a 2/2. I wouldn't be building around Ajani as a recursion engine.
Multiple +1/+1 counters will win you games whenever it starts happening. The three Cat ultimate is another thing that will eventually just win the game regardless. Ajani is definitely a good aggressive card that will kill your opponent if played on turn four, but it is a resilient long game win condition for a blue-white control deck too. Ajani is among the best rares in Core Set 2019.
We said Electrify was fine for four damage for four mana, so Spit Flame at one less mana for the same effect is always going to be good. But it is just good if you cast it once and turns to absolutely insane like Sarkhan's Unsealing if you cast it twice. It turns out there aren't a ton of Dragons, but the common Sparktongue Dragon is fine to play a couple of. If I draft Spit Flame I'm not expecting it to crush my opponent all the time, but I'm assuming one or two games a draft it does something really amazing without a lot of cost. It is an easy first pick over basically any non-rare.
Evaluating rares is one of the more difficult parts of Limited, but hopefully this article has helped provide some of the tools you can use to figure them out on the fly without the full research project getting actual play data on all of them always ends up being.