Heyyoo!! So, disclaimer, this is just an idea for his ult. I just thought of this lol, and I think that it might be a good start, so I'm wondering what other people would think about it! ^_^
Anyway though, so, I think Aatrox desperately needs a rework, because he just has no direction in his theme. But like, his story's super cool, it's just that his kit doesn't reflect it. (Literally all his current ult does it deal a bit of damage around him and gave him attack speed. It also gives him a teensy bit of attack range and make his wings look cool lol.)
So currently, his kit is leaning towards someone who leeches the strength of enemies as the fight continues, but that's really not at all how his character is, and I think it'd be great to have an Aatrox that fits his lore, because his lore is honestly super cool! Go read it if you haven't read it. ^_^ (Also I think it's better to change gameplay to fit a theme, than to change theme to fit gameplay in a rework, because the theme is who the character is, so that's like deleting a character and just making another.)
So what I take away form his lore is that he's an immortal legendary warrior, who appears in crucial moments of history and turns the tide of battles, for better or for worse. In his lore he appears before the men and urges them to fight on, but after they finally win the war, they come home and realise they've become the monsters that almost destroyed them. For his ult in particular, I think it should be like that moment, when he urges them on! Beacuse that's like, his most distinctive thing to me. More than a warrior, he's a manipulator who dictates the course of history as we will. So, I think his ult should reflect that! So something that can turn the tide of a battle in terms of rallying people, but because the people he rallied ended up becoming monsters themselves, I think that it should represent in some way him giving a dark and twisted power to his team which is like a "Has science gone too far!? D:" moment! :p
This makes me think of The evil King's army from the Eragon books! Super cool stuff! For those that don't know, his army's really powerful, because each individual soldier is really difficult to kill and goes on like a Zombie, because the Evil King (I can't remember names lol, I think Galbatorix.) cast a spell on all his soldiers that make them unable to feel pain! That makes them become terrifying monsters which are very difficult to fight! D:
And so I think that something similar on Aatrox would be good! So, here's my idea for his ult. There are two variations, not sure which would be better. The ult essentially has a buff to allies and a debuff to enemies, and I don't know if it should just be in a very large AoE around Aatrox himself, or if the buff should be global and the debuff should be in large AoEs around allied champions. Personally, I prefer the latter global buff thing, but I guess I'm open to it being reduce to just a large AoE around Aatrox, but I think it should affect all 10 champions in a teamfight scenario. Anyway, I'll explain the global variant, because I prefer that one! :3
So here's my idea: When you use your ult, it will globally restore HP of all allies depending on damage they've taken recently, like the healing aspect of Ekko's ult, and it'l also give your allies a damage reduction buff! Also, in the AoE around all allied champions, it'll fear every enemy unit for like half a second and also give them a decent slow that decays over two seconds. The damage reduction buff of allies will start off small-ish (Depending on the rank, at level 16 it'd start off pretty dece.) but increase over time! The buff itself will have a very short duration, however the duration is very slightly extended for your entire team whenever a champion damages an enemy. So that means the entire team needs to work together to keep it going! If only one person is damaging, then the duration won't last very long, but if the entire team is dealing damage, the duration will last quite a bit! Also, I like the possibility of two things: One, a window of weakness at the end of the duration. Possibly just a slow when it ends, a bit like Blitz's W. I'll explain why in a bit. The other possibility i like the idea of it giving it a stupidly long cooldown, like 5 minutes or something. My reason for that is I think it should be an incredibly high impact moment, and letting it happen in each teamfight would undermine that both thematically (Having it each fight would reduce its "WOAH THIS IS HAPPENING!" effect), and mechanically because it'd have to be toned down to make it fair to give it to Aatrox's team each fight, which would make the ability underwhelming! :(
Now I'll explain how I think it'd play out and interact in the game! I think essentially, this would an Aatrox ult a really awesome moment! Where the gives the team a chance to just dive head first into the battle and come out on top, and it makes the enemies have to back pedal and stop the fight! If everyone co-ordinates and all attacks at the same time and the enemy team can't disengage, it'll be a super good momeny for Aatrox's team, and also to the enemy team I think as well, but showing them the horror the the ancient people must have felt when Aatrox joined the enemy camp, and then suddenly out of nowhere they were getting destroyed! I think it'll just be a super awesome moment! I think it'll also give Aatrox clear strengths and weaknesses in terms of team comps. He'll work amazingly in engage comps with like Malphite and Hecarim and Yas and stuff, but he'll work really poorly against disengage and protect the carry comps, which are really support and defensive. (Although honestly I'd love to see an amazing wombo with Aatrox, and Kled lol!)
So I think this also has great potential for being an awesome moment for when it does work, but it needs to be both sided, so it's an awesome moment when it fails, too! Which is why I had those two possibilities! In terms of counterplay, I think that it should be that if the enemy team disengages properly, they're really rewarded for it! The slow if the duration of the buff doesn't get extended enough gives the enemy team a chance to punish Aatrox's team if they don't take advantage of it (And I think it sort of works thematically too, because if you were on the brink of destruction, and Aatrox was there to spur you on, but not even THAT worked, you'd probs just be ready to roll over and die lol. XD). Also, the super long cooldown gives the enemy team an opportunity to do decent fights without having to be constantly worried about a sudden Aatrox ult ruining it. XD Which I think is necessary, because you can't have half the player base paranoid for the entire fight. Possibly also a glboal notification for when Aatrox's ult is back up, like with Corki's passive?
A possible disadvantage to having such a long cooldown though, is that it sort of leaves Aatrox without an ult of his own. I don't think that's automatically a problem though, because look at Taliyah and Rek'sai, which such situational ults you won't be able to use each fight and don't even deal damage!, and look at Kog maw and Udyr, who essentially have four basic abilities and their kit works fine. However, there are options to both give Aatros this ult, and also a normal ult, like maybe the one he already has. I can think of two things: One, put it on his passive. He can activate it by left clicking his passive, which really replaces his passive with a third summoner spell but w/e, haha! We have stuff like Bard's ult, and Aurelion Sol's passive, and Azir's passive, we can have an activeatable passive. XD This could replace his current passive, of co-exist with it. Who knows! (Although I don't really see how his current passive meshes with his theme. :/ immortal and undying aren't necessarily the exact same thing, and I think they don't match together. Maybe if his passive plopped him back to base, like the shades from Eragon (more Eragon references lol)) And a section option, which I think would be cool is, give him two ults that both go on his R key! Possibly something like Yorick's Q, or, more likely, make it so he has a normal ult, but while he holds the alt key, his ult turns into this other mega ult with a 5 minute cooldown! :D Although personally I prefer the option of just not giving him a normal ult and letting his ult be a situational utility ult, like Taliyah's, or Rek'sai's. (Oh golly can I just say that I love utility ults!? They're so cool!)
WOW! This was a long post! XD Thank you so much for reading this far! I hope to hear your thoughts on it! ^_^ (Especially the thoughts of any Rioters passing though. ;) Hey, I wouldn't mind you guys passing this on up a couple ranks, nudge nudge wink wink.)
Edit: Oh yeah, I forgot to mention, of course something like this would involve really big flashy graphics, sort of like how people look real flashy while ascended, possibly, and like, a global announcement like Sion and Rek'sai's ult, like, Aatrox yelling out "FIGHT" or something, and also probably a really decent channel, a bit like a Karthus ult. Can the channel be broken by CC? I don't know if that'd be good. :P I'm leaning towards no. Although maybe being hard CC'd would exclude a particular champion from the buff?