My own Karma rework
Hello, fellow summoners! 
I've read MANY player-made threads about how Karma failed as a rework some years ago, and trust me, I share your pain. I've been a main Karma for years, and with time I've been able to do nothing but contemplate how every single thing I loved about her got stripped away. After checking some of your rework proposals and the feedback they have received, I've come to the conclusions that, even though they seem AMAZING, Riot will not show great interest in implementing them on her.
However, inspired by the passion that connects us and some of your awesome ideas, I've come up with my own rework proposition. It's more focused on leading team-fights and counter-attacking aggressive enemies than poking and spamming shields. And more importantly, it involves fans and shield bombs. I hope you like it and maybe by chance a red will find it and get some inspiration :)
So here it is: (Note: Numbers are subject to change)
Auto-attack: Range: 500 Karma sways one of her fans to send forth a small pulse of energy to her target.
Passive: Indomitable Spirit INNATE: Karma gains 1% Tenacity for every 2% HP she’s missing.
Q: Heavenly Wave / Soulflare Mana cost: 40/45/50/55/60 Cooldown: 7/6.5/6/5.5/5 seconds Range: 600 Stops movement?: Yes, but only during the initial cast ACTIVE: Karma sends forth an energy wave from her fans, dealing 50/90/130/170/210 (+50% AP) magic damage to enemy units in a cone, and healing herself and her ally champions by 40/55/70/85/100 + 5% (+1,25% per 100 AP) of their missing HP.
MANTRA BONUS: Karma releases 3 Heavenly Waves over 6/5/4 seconds. Instead of cones, the waves take form of novas that affects all units around her in an 800 units radius.
**W: Focused Resolve / Spirit Bond ** Mana Cost: 70 Cooldown: 16/14.5/13/11.5/10 seconds Range: 675 Stops movement?: No ACTIVE: Karma revolves the air with a fan, forming an ethereal tether between herself and another champion for up to 5 seconds, and increasing her movement speed by 15/17.5/20/22.5/25% for the duration. If the distance between Karma and her target exceeds 800 units, the link breaks. In addition, the tether applies extra effects depending on the target, for the duration. ON ALLY CAST: Increases the target’s movement speed by 15/17.5/20/22.5/25%. ON ENEMY CAST: Grants true sight of the target, and slows it by 15/17.5/20/22.5/25%.
MANTRA BONUS: ON ALLY CAST: Whenever a side of the tether gets healed by an item, skill or summoner spell, the other side regenerates by 20/25/30% of the amount. This effect doesn't stack with itself. ON ENEMY CAST: Transfers 20/25/30% of the damage Karma and her Soul Shield receive to the target, even if the Soul Shield is casted on someone else.
E: Defiance / Reprisal Mana Cost: 60/65/70/75/80 Cooldown: 10 Range: 800 Stops movement?: No ACTIVE: Karma summons a Soul Shield on herself or an allied champion that absorbs 80/120/160/200/240 (+60% AP) damage for 4 seconds. If the shield gets broken, it bursts a surge of energy that deals 60/70/80/90/100% of the shield value as magic damage to all enemy units around her target, in a 600 units radius.
MANTRA BONUS: Increases the damage dealt by the surge by 40/80/120 (+40% AP). In addition, the surge slows all enemies hit by 30/40/50% for 3 seconds.
R: Mantra Mana Cost: Free Cooldown: 40/30/20 seconds Range: Self Stops movement?: No Note: Now Karma does NOT start with a rank in Mantra.
PASSIVE: Karma empowers every fifth basic ability cast, placing it on the same cooldown as its basic form upon cast. ACTIVE: Karma empowers her next basic ability within 8 seconds, placing it on the same cooldown as its basic form upon cast.
You can't empower a single ability twice in 10 seconds.
Some insights: This Karma’s kit focuses on balancing the battlefield by inspiring, healing and protecting your allies while demoralizing and punishing your enemies for their hostility. By removing her overwhelming poke and burst, I make some space for utility based on appropriate timing and targeting. Also, this Karma is designed to create opportunities to turn team-fights into one’s favour (“Guess what’s about to hit the fan”).
P: Her passive is made to compensate her short-mid range and low early sustain by creating windows of opportunities where Karma can turn things into her favour. Plus, it fills the Ionia fantasy of resisting adversity through a courageous, resolved leader, and reminds of the old passive idea of “the weaker I get, the stronger I become”.
Q: Heavenly Wave got inspired from the previous Karma and her famous fans. It deals a not too high amount of spammable damage while healing your allies by an amount that depends on how hurt they are. At early levels, it’s not a big heal, but has a strong lategame potential. It also gives Karma the chance to follow different build paths, and the spammable component helps build up stacks for R. RQ: This ability is designed to help your team resist and deal sustained damage. The long intervals between waves give the enemy bursty champions the chance to get their job done before you land all your heals and nukes.
W: A simpler, slightly more intuitive version of old W. The long duration and low buff/debuff allows Karma to constantly reposition herself during a fight and keep acting without becoming an Ahri. It also inspires allies to engage in combat and escape safely. RW: This is one of my Karma’s most complex, yet rewarding mechanics. It punishes your enemy for its hostility against you AND your shielded ally, or allows you AND your ally to share a strong burst of heal when in combo with RQ.
E: Shield bomb! Yes, shield bomb, but not as reliable as it used to be, because that’d be OP. Its reactive damage triggers when your enemies get too aggressive, so it’s good for demoralizing them or forcing a change of tactics like “let’s attack this unit instead of the shielded one”. RE: Mantra doesn’t strengthen the shield because that’d made the offensive component too unreliable, but makes it more punishing instead. In team-fights, you can use unfriendly fire in your favour to deal some pretty decent AoE damage and light crowd control.
R: Big old famous mantra, but with some little tweaks: You get two charges of Mantra, instead of one. One of them is a passive that forces you to choose your skill order carefully, and the other one is an active to keep it reliable and allow some sick combos. The other tweak is that you can’t use it before level 6 because that’d be OP.
Primary purpose of each R Combo: RQ+RW (ally) = Godly heals for you and 1 ally and decent heals for the rest of your team. RQ+RE = Great AoE potential damage RW (enemy)+RE = Good peels and enormous counter-damage potential
Recommended stats: AP: Main source of power. CDR: Your Q and R are designed to be used as much as possible. Shield/Heal boost: A Secondary source of power. HP: Your low mobility and short-mid range require you to get a little bulky. Plus, it strengthens your Q’s self-heal, therefore your RW’s shared heal.
Mantra lines: Mantra 1: Sae Eleisa Tera Vi- (Discover the meaning of-) Mantra 2: Irnae do Varia- (Open up and embrace-) Mantra 3: Koe Ionia Kaoda Vi- (Ionia shares its story of-) Mantra 4: Di Soura Irnae Go Vi- (Let light open the path of-) Mantra 5: Lo Souka Bui Roth Vi- (May heaven acknowledge the struggle of-)
Soulflare: Kya! (Hope!) Spirit Bond: Diora! (Harmony!) Reprisal: Jia! (Pain!)
As a conclusion, I'd like to say that this Karma is not intended to provoke teamfighs or abuse squishy targets like the current Karma does (among other things). Her old lore was about empowering herself and her people against adversity and I intend to project that through defensive AoE effects with agressive components that respond to enemies' actions. She's still vulnerable to assassins and bursty champs but with the right combos and good timing you'll almost always be able to turn the tables in your favor.
Hope you like it!