I suggest a nerf/rework to the atma's impaler item. I think instead of adding +dmg to a champions base attack it should on attack, do the extra +dmg as an additonal hit. In other words, a champion would hit with their base attack doing i.e. 60 damage, then right after atma's impaler would hit for another i.e. 80. Changing this would prevent what I believe are exploitable item specs on characters like Katarina. Going 4 Warmog's Armor, Atma's Impaler, and any form of Boots allows her to A) not die because she has so much life, B) kill everyone because atma's impaler gives her 200+ attack based on her HP C) take special advantage of her ultimate ability Death Lotus which scales significantly with attack damage.
In essence, not only does she become the best tank via shunpo dodge/6000 hp but also the best DPS as well. Limiting atma's impaler to a second-hit effect I think would prevent such drastic scaling on her ability and balance the game. Not only that, but also the damage could be considerd magic within the rework, allowing players with magic resist an opportunity to reduce the effectiveness of atma's impaler as a strategy. As it stands, it is a pure physical buff thus armor is the only thing that negates it. However, Katarina converts all that physical damage into magical instead, how can a player stack both Armor and Magic resist enough to counter both those devastating attacks? Anyway, that is my rant about atma's, hopefully my suggestion is taken into consideration.

well, your post is hard to go through but i see your point. i don't think atma is at fault though, the effects are fairly balanced. id say the best fix is to make the cd of katarina's ult longer, it's way too short atm.

yeah her ult is very powerful, but i do think that it is easily countered with stuns/cc. what i was complaining about is how if you go atma's//HP then you easily live through 5-6 CC's to be able to ult again

keep in mind im not proposing a reduction in damage to atma's, i simply want the damage it gives to be separate from an increase to base attack damage that an item like B.F. Sword would give

Honestly her ult is rather weak against good players. It requires near suicidal placement, can be interrupted, and has almost no range/slow to keep you in it.

who can get 4 warmog's armor AND atma's AND boots in one game????

okay well thats the end of the game spec, you start with regrowth pendant, 3 hearts of gold, atmas and boots. much more feasible with the same result. then you get 1 warmog from the pendant and then replace each heart with warmog after warmog. ive done it at least 6 times today, never fails.