I think Shivan Dragon would be a fun include at common.

(How the mighty have fallen)

This is insanely cool

This being 6 mana is pretty tough. Thankfully, it's green.

This one feels like a pretty niche card that could see play in the right deck, but I'm not super keen to cast this in any format.

Again, the 5 mana on this is such a steep price. And it requires set up.

Kinda sick for Cube, though.

Not bad. Cost of 5 is pretty steep though. I'll say that this one isn't enough to see significant play.

The closest comparison I have here is Ertai.

This is my early pick for the most playable one in Constructed.

Ward 1 isn't super impressive, but Lifelink is very nice. I do like that it dodges Go for the Throat.

So the only way WotC was able to green-light this design is to have it use a physical reminder as part of the execution. This limits the design space, but not to a degree that it couldn't be printed.

You'll notice that Loot doesn't have any tracking mechanics as part of the ability. Being a mythic rare, that card gets a pass in terms of design.

Here are the other 3 cards with Exhaust. More counters. Redshift puts a bunch of permanents into play, which serves as a physical reminder, still.

If design them all to have some sort of built-in tracker as to having activated them, that can serve as a memory helper.

Check out these 8. Almost all of them put a +1/+1 counter on them. This serves as a reminder that it has been Exhausted.

Using a token (like the Red card here) is another way.

Activating an ability only 1 time has an issue that WotC doesn't like to flirt with, which is that it has memory issues in paper.

After you Exhaust a creature, then a handful of turns pass, it's a pretty ripe space to forget (or even, 'forget') that it was activated. But! There's a solution.

Lastly is Necrodominance. The card is like $3. It's still a powerful way to draw cards and the most recent way to draw a lot of cards recently got banned.

I don't pretend to know exactly what will cause a card to spike, as that is a fools errand, but I like scooping up unique and powerful cards.

Kozzy doesn't have the cost discount that Emrakul does, but comes at a smaller price around $7.

I tend to like mythics that have a lot of untapped potential. Emrakul is under $10 and that is good enough for me to scoop up a playset.