But why on earth would we want to end our turn early, anyway?
Removing Horrific ETB triggars
Phyrexian Dreadnought, Eater of Days, Hunted Horror, Boldwyr Heavyweights each cause significant problems when they enter the battlefield. Phyrexian Dreadnought dissolves any board state we might have; Eater of Days loses us our most important economy - turns; Hunted Horror gives the opponent an arguably better board state; and Boldwyr Heavyweights puts 3 of our enemies' best creatures on the field. With Obeka, Brute Chronologist and her like on the field, this is not the case. While their triggars are on the stack, we end our turn, skipping to our End Step and erasing those cataclysmic downsides behind for good.
Allowing Creatures to be Remain Longer than Planned
Kroxa, Titan of Death's Hunger should die as it enters the battlefield, but if we "End the Turn" before this ability resolves, we get to keep him. Even better, because of the order of the stack, his second ability triggars first, so we can end the turn after that ability. Similarly, Hellkite Courser cheats in our Obeka, Brute Chronologist, but it should go back to the Command Zone "at the beginning of the next end step" - we can skip that step and jump straight to "End of Turn", leaving her to fight another day.
Exile Off-Colour
Identity Thief and Mystifying Maze both can blink a threat from existence, but "at the beginning of the next end step" they get it back, right on time to threaten us, again. If we skip to "End of Turn", that triggar never happens, leaving them with a missing threat and in Identity Thief's case with a hopefully large threat still on our side of the board.
Keeping Tokens
Feldon of the Third Path, Flamerush Rider, Jaxis, the Troublemaker, Saheeli Rai, Flameshadow Conjuring, Splinter Twin, Mimic Vat each create various tokens of creatures we or our opponents own. Again, they return from whence they came "at the beginning of the next end step" so we "End the Turn" and keep them around. It would be impossible to pick an MVP among these, but Flameshadow Conjuring's ability to double up creatures every time they enter is excellent, and they don't even need to be "cast" to gain the triggar.
Kiki-Jiki Combo
Even worse than tokens staying around is an infinite number of tokens staying around. The same trick of ending the turn early can be used to keep all the tokens generated by the traditional Kiki-Jiki, Mirror Breaker / Splinter Twin + Zealous Conscripts /Pestermite combo. The only question would be: will you need to keep them?
Maintaining Control
Puppeteer Clique, Zara, Renegade Recruiter, Hate Mirage, Gruesome Encore each allow us to gain control of our opponent's creatures, either from the graveyard, hand, or battlefield. By ending the turn early, we get to keep our enemies' creatures for longer than we should.
Unnatural Speed
Cards like Sneak Attack, Purphoros, Bronze-Blooded and to a lesser extent Through the Breach (pretty much only there to cheat out It That Betrays) allow us to pay a significantly reduced fee to get a creature onto the board at instant speed. Similarly, Ilharg, the Raze-Boar serves the same function, though a little more fragile due to the tapped and attacking phrase. Tapping Obeka, Brute Chronologist stops these triggars from resolving, allowing us to build our board with more pace.
Unearth
Both Sedris, the Traitor King and Corpse Connoisseur use the Unearth mechanic to help us to keep utilising our graveyard. However, that ability requires us to exile the creature at the beginning of our next end step. Cancelled, leaving us with a permanent...permanent. Note that while Sedris, the Traitor King card text mentions "at end of turn", but the oracle text for Unearth is "the beginning of the next end step".
End of Turn Reanimation
Following these rules of ending the turn before we have to, we have a bunch of cards that allow us to bring things from our graveyard (a tactic we double-down on, in a bit). Cauldron Dance gets a creature out of your hand and another out of your 'yard; Footsteps of the Goryo grabs any creature from the 'yard for 3; Goryo's Vengeance is often a worse Footsteps of the Goryo, grabbing a legendary only, but costing less; Whip of Erebos recycles a creature from the 'yard for 4;Apprentice Necromancer swaps places with something in the 'yard as a cheaper Doomed Necromancer with 'downside'.
Mana
Only one, here, but if we end the turn just as Lotus Field enters, the "sacrifice two lands" triggar is cancelled, and we get to tap for value next turn without losing anything.
Extra Turns
Using Alchemist's Gambit, we can take an extra turn for 3 mana, as long as we end the turn before its non-Cleave triggar activates on the next turn...a little nod to the Final Fortune I would be using if those cards had modern fronts.
