Kidney Beans- a joke about Up the Beanstalk
Glarb was objectively created for EDH (like so many legendary critters these days). He could also be played in Legacy (perhaps) in an Up the Beanstalk shell, as he pairs very well with cards like Force of Will.
So hey, let's see if he can work in modern.
Here's the theory: there are many, many ways to take advantage of Glarb's 4-drop requirement, such as evoke, split cards, delve, X costs, and double-faced lands. Of note, I checked the rulings on all of these (as well as many other types), but if I got something wrong, please tell me.
Long story short, you can get away with playing heavy CMC's with or without Glarb on the field, but with Glarb on the field, you can gain pretty good card advantage and take advantage of some good synergy.
Glarb himself is a mixed bag. Being a full sultai 3-drop is aggravating, and he has no ETB effect, which is REALLY aggravating. You also probably can't take advantage of his effect the turn he hits play because you've gotta dump the mana into getting him on the field, so you probably can't play spells from the top of your deck, and you probably played a land this turn, so you can't play lands from the top of your deck. Plus, he doesn't have haste, so he can't do his delightful surveil effect. On the other hand, he's fetchable with Green Sun's Zenith, making him much more reliable as an engine. He's blue, so you can pitch an unneeded/inconvenient copy to Force of Negation. He's got a decent ass, so he's not boltable. He comes with deathtouch, so he's a decent wall and a potential one-for-one against something nasty. And his surveil ability helps himself as well as your delve spells, and your synergy in general.
The deck itself has a pretty simplistic plan that relies very heavily on surviving the opening without being too far behind, and to that end, there is some good synergy with Glarb. 25 lands means you're probably not going to miss a land drop, and Glarb will help make sure the excess lands don't get in the way once you escape the first few turns. Ice can be used to tap out a land of opponent's. On the play, this is potentially a Time Walk, on the draw, it's not as good, as you've got to use it on opponent's turn 3, but can still buy you a turn either way, even if it's just stopping some early damage. Force of Negation protects against combo decks going off before you hit your groove. Green Sun's does its famous accel into Dryad Arbor, and keeps the deck fat with ways to get Glarb and/or answers. Fetch lands into surveil lands is an excellent turn 1 play that gives you selection and fixes colors.
Once Glarb is fielded, you've got 41 cards in the deck that he can do something with off the top, so the math is definitely on your side. Since he plays lands, the accel helps with this quite a bit, as each turn you build up the inevitability.
Will it hold up in Tier 1 Modern? Nope. Is that super lame? Yep. Oh well, was still a fun idea.
Feedback appreciated.