More and more AP Sejuani Toplane OTPs are appearing in master-grandmaster korea: https://www.onetricks.gg/de/champions/ranking/Sejuani

Especially after Recent Buffs in 14.9 Sejuani Top is back, STRONGER THAN EVER.
Sejuni has not only great lane, being able to stomp many opponents in a VIDE variety of matchups, but also really strong early/mid skirmishes and lategame teamfight usefullness

In Early Levels 1-5 you want to let the opponent push you in while trimming the wave slightly, setting up a freeze if possible and poking your opponent with W, Comet + Scorch. (Be careful not to push the wave too much)

You Spike a lot at Level 6 so wait it out in matchups where you seem to struggle pre 6
Seju is a Mid Game Powerhouse and this Build enhances he midgame even more. Levels 7-12 You will outperform almost any Toplaner in Skirmishes

I know this is in Korean but its still nice to see some of his Gameplay:

Korean video on Early Lane

Early Skillorder most Games: W -> Q -> W -> E -> MAX W -> MAX Q

These OTPs have huge variety in their builds and even the core Items, which I had a hard time understanding before. After large amount of testing on a fresh account (100+ Games in Silver-Diamond EUW) and watching other Sejuani OTPs i have found the 3 main build variations:

1.Liandries -> Fulltank (IBG/Kaenic) Probably most reliable all around as you get really tanky later. Good into Tanks, and extended Fighters. More expensive than Rylais but very good One-Item Spike. Credit to u/Chitrr: https://youtu.be/gW-i4XGiaRo?si=VlKjf784slZk2yoZ

2. ROA -> Liandries: Highest Dmg, best Skirmishes, worst 5v5 due to lack of tankiness, especially bad vs lots of max HP dmg, (i.e. good vs Jax, Irelia to completely destroy them in lane and snowball) Mejais, Rabadons are good if you get fed, turning it into more of an assasin build

3. Rylais Rush: Great into ranged matchups or where slow is really good (i.e. Jayce). Cheapest 1st Item Spike, lowest Dmg https://youtu.be/sV_LRKjlt84?si=bkRZa4JHhR9uAnG9

Both Top and Mid are fine but i prefer it against melee champs who can be spaced easily. Once you get Ionian Boots you can W -> W without the Stacks falling of. With this build Q is mostly used to disengage while u try to space your opponent.

Runes: Best Overall Setups are Grasp or Comet, depending on Matchup, Grasp is better if you need to be able to contest in AA range: (Yasuo, Yone, Renekton) Comet is better in most cases as it gives you more oportunities to solokill, more surprise dmg and better poke.

Comet, Manaflow, Transendence, Scorch or

Grasp, Demolish, Second Wind/Flex, Overgrowth

I tried Chitrrs secondary transendence page, but much preffered Cookies+Cosmic Insight (the classic) Shards: Cdr + AP/Scaling Hp (preference) + Flat HP

Another korean OTP takes Aery using the Rylais build, this could be a whole other debate on its own but in most cases it comes out to be similar damage as Comet. I like aery vs Teemo as he can walk out of coment too easily