Support Karthus Build

General

1. You're a healer, Harry.
2. Even though Karthus is not typical support, you are gonna support your team very effectively. With heals, shields and buffs:
• Heal summoner spell.
• Guardian and Font of Life runes.
• Redemption, Locket of the Iron Solari and Moonstone Renewer and other items.

General

1. Your first rush is Redemption.
2. Your second rush can be Locket of the Iron Solari (vs AoE), Moonstone Renewer (sustain).
3. Also, Echoes of Helia is pretty good because you can proc it consistently with Font of Life (slow/cc).
4. Rush second Locket if your team already doing teamfights or when an enemy team has champions with super aoe damage (example: like Fiddle's ult). Otherwise, get Moonstone Renewer #2. The third item should be whatever you did not buy - Locket of the Iron Solari or Moonstone Renewer. That's your core.
5. Another decent item if you have carry/strong bruiser/strong tank is Knight's Vow.
6. Try to use summoner spell Heal on cooldown. With Moonstone Renewer, ideally there should be at least two people for maximum healing effect.
7. Later in the game, for maximum support - you can sell boots for sixth item.
8. You can get items like Ardent Censer (some auto attackers needed) or Staff of Flowing Water. It will be triggered often enough that it will be worth.
9. Interesting item is Cryptbloom. If you want to go full healing, you can get it like #4+ item.

Runes

1. With Cosmic Insight rune from Inspiration tree:
• Redemption and Locked of the Iron Solari has 81.92 sec cooldown (down from 90 sec).
• Shurelya's Battlesong has 68.12 sec cooldown (down from 75 sec).
2. Guardian is important rune. It is going to provide tons of shielding. Remember that you need to be close to your allies to proc it.
• You can also manipulate it - for example, you can stick to one ally, or avoid some spells that's gonna only waste it.
3. You will be triggering Font of Life effect, which will heal your allies. It also chains off Moonstone Renewer!
4. Font of Life total healing is not properly calculated in a post-game lobby. Value is bigger in the game vs. what's displayed in statistics. You heal more!
5. Another important rule is Cosmic Insight, it reduces cooldown for your active items (so more heals/shielding) and Heal summoner spell.

Redemption

1. Try to use Redemption on cooldown, when your allies are missing some health. It is best to use when they are grouped. Especially if you already have Moonstone Renewer, it is best to wait (or ping) until they group together, so you can have them all healed.
2. Remember that you can use Redemption for the damage. However, in general, it is not worth it. Keep it to heal your team!
3. Be careful when using Redemption while you are dead, and you are about to be respawned. The camera will go to your position, and you can cast it in the spawning pool by mistake. Watch out for bad timing!

Champion

1. Late in the game, you can sell boots and go for sixth AP item.
2. You can stop push by using Wall of Pain (W) on minions.
3. You can die in strategic positions and prevent an enemy team from pushing/defending turret.
4. You can start casting your Requiem (R) when somebody is dead and has 2 seconds left, so you will hit him instantly with R (i.e Fizz won't use E to dodge it).
5. Enemies in your base? Use Defile (E) before taking portal (frost-gate) - you will damage them on your way!

Riot

1. Ask your allies to help point out when you should use Requiem to get kills in different lanes.
2. Lay Waste is very strong at farming minions and harassing enemy champions.