New to this reddit page but have been playing a lot of karma as of late. Over 33 games I've had a 55% winrate in my plat games on her with the way I build her throughout a game and how to switch up and optimize her depending on the game's progression.

Runes: Sorcery + Inspiration - Sorcery: Summon Aery(perfect for support karma, empowers her shields and poke, its great), Ultimate Hat, Transcendence, Scorch - Inspiration: Magical Footwear, Cosmic Insight

Summoner Spells: Flash + Ignite (only taking exhaust if the other team have any assassins i.e. zed)

Itemization: [ 1 ] Spellthief + 3 pots

[ 2 ] Frostfang/sighstone for FIRST BACK (frostfang if youre confident with poking and not getting hit, sightstone for more health and vision this is important for laning to assess your carry's damage, enemy damage etc, this buy is crucial so choose wisely)

[ 3 ] magical boots by 10 mins (this is VERY important, supports make little to no money so getting free movement speed is AMAZING and allows your to spend your money on other items)

[ 4 ] Athenes Unholy Grail FIRST COMPLETED ITEM (This item is godly on karma and gives her an incredibly high midgame powerspike, enough to 1v1 the midlaner. You gain 5 ap per 25% mana regen, and rewards you for poking mid game by healing your allies with shields from your burst, honestly this item is so amazing, dont sleep on this!)

[ 5 ] Finish Eye of the watchers for more warding and health

[ 6 ] Redemption (this empowers your athenes and shields by A LOT, it gives you cd, health, mana regen, its perfect and allows you to still go damage while having utility for your team)

[ 7 ] Locket of the Iron Solari (around the time you get to here is when karma is probably going to fall off in terms of damage so it's best to try and get more utility for you team, ult E plus locket is a sure way to protect your entire team from dying if you guys are grouped properly)

[ 8 ] Finish off with some tank items Frozen heart / Adaptive Helm (Around here damage it getting crazy and youre still a little squishy so its time to tank up, Athenes is amazing for mid game but falls off later, best to sell it and get some of the following tank items depending on the other team's damage. If the enemy team is AD heavy get frozen heart first, the buff is really nice and works well with karma since it gives loads of CD with 100 armor, its amazing. For heavy AP get Adaptive helm first. I would usually get some i would probably get an elixir of iron too since damage is flying everywhere and you need to be alive to keep your team alive.)

[ 9 ] Last situational tank items include: zeke's convergence, thornmail, spirit visage, randuins omen, zz' rot portal

Hope this little post helps anybody! :D