@ChubbyRain Frankly, I think they're finally managing to hit their stride when it comes to powerful-but-not-broken Walkers for eternal. It feels like they've been adjusting the dial of PW power level slightly upwards and have finally found a sweet spot.
Starting about in M13, I feel like this conversation happened at Wizards:
"Jace TMS is broken as heck, and almost no other Planeswalker matters. Can we fix that?"
"Well, let's start printing 4-cc walkers and make them powerful."
"Careful, though. We can't just reprint something on the level of Jace."
"Fair enough. We'll start turning the dial slowly, and increase the power until there's a problem."
So we went from the 4cc walkers worth a poop that were not named Jace being Ajani Vengant and Garruck Wildspeaker into more interesting forms. The evolution went something like:
Chandra, the Firebrand (M13)
"This one is interesting, but it saw no play. Looks like we can turn up the dial."
Ral Zerak (Dragon's Maze)
"Hmm, looks like combo-ing with Stasis isn't really a thing anymore. Alright, lets keep turning the dial up."
Liliana of the Dark Realms (M14)
"Hm, we thought this was interesting, but I guess it's not quite good enough yet. Perhaps the problem is being a mono-black walker? Well, lets keep hitting that dial."
Koria, the Crashing Wave (Born o' the Gods)
"Okay, I guess we can't fix Kiora just by tweaking her land matters + damage prevention abilities. Perhaps Gush does doesn't need such a flimsy body? Well, back to the drawing board."
Chandra, Pyromaster (M15)
"This one actually broke into fringe playability in Legacy! Hooray! I wonder if we can push it just a TAD further, though?"
Daretti, Scrap Servant (COM 14)
"More of a lateral move than increase in power, maybe, but we managed to make another fringe playable. Hooray us!"
Narset, Transcendant (Dragons of Karkir)
"Okay, HERE we go. Is letting you draw cards and double spells enough? And, just in case you're worried about protection, let's give her ALL the loyalty. Gentlemen, we hit playable in VINTAGE!"
Nahiri, the Harbinger (Shadows over Innistrad)
"Great, another playable -- and in an underutilized color combination to boot! I think we have the formula, finally. Make sure the walker can replace itself, protect itself, and win the game. Removal is fine, too. I'm a bit scared to push the cards any further, but this seems like the perfect eternal power level."
Kaya, Ghost Assassin (Conspiracy 2)
"Can we follow our new formula to push underplayed color combinations in Eternal? Let's see!"
Dovi Baan (Kaladesh)
"I think we've got the formula down pat. Let's see if we can keep printing things around this level in PLAYED colors to keep things interesting!"
Chandra, Torch of Defiance (Kaladesh)
"Aw hell, let's just see HOW FAR WE CAN PUSH THIS without breaking Modern."
Both Power 9 top 8s:
Nahiri Gush: https://www.mtggoldfish.com/deck/452374#online
Nahiri Oath: https://www.mtggoldfish.com/deck/480356#online
Even though Nahiri Oath only runs 1 Nahiri, Andy (Montolio) said it overperformed for him while Void Winnower underperformed. I've tweaked the mana base slightly, cutting Void Winnower for Sun Titan, and finding room for a second Nahiri and Balance, but refuse to actually play it in an event until CN2 is made available.