Don’t Throw a Tantrum
Aftershock
After immobilizing an enemy champion, increase your Armor and Magic Resist by 35 + 80% of your Bonus Resists for 2.5s. Then explode, dealing magic damage to nearby enemies.
Damage: 25 - 120 (+8% of your bonus health)
Cooldown: 20s
Resistance bonus from Aftershock capped at: 80-150 (based on level)Why?
Aftershock is a great rune for entering a gank with [Q] providing you the resists to survive and a bonus burst of damage with the explosion.
Font of Life
Impairing the movement of an enemy champion restores Health to you and the lowest health nearby allied champion.
70% effect for Ranged Users.
Cooldown: 20sWhy?
As Amumu your [R] has the opportunity to provide a ton of healing in a teamfight if you're able to hit multiple targets.
Conditioning
After 12 min gain +8 Armor and +8 Magic Resist and increase your Armor and Magic Resist by 3%.
Why?
Conditioning on Amumu allows you to scale into the mid game as a massive tank alongside Aftershock and Overgrowth.
Overgrowth
Absorb life essence from monsters or enemy minions that die near you, permanently gaining 3 maximum health for every 8.
When you've absorbed 120 monsters or enemy minions, gain an additional 3.5% maximum health.Why?
Overgrowth is likely the best rune in this slot primary due to Amumu's fast clear speeds and lack of major value from the other 2 options.
Transcendence
Gain bonuses upon reaching the following levels:
Level 5: +5Ability Haste
Level 8: +5Ability Haste
Level 11: On Champion takedown, reduce the remaining cooldown of basic abilities by 20%.Why?
Transcendence is a great rune choice on Amumu as he likes to build all of the CDR tanks items, allowing him to go over cap and still make great use of the extra AP gained.
Waterwalking
Gain
10 Move Speed and13 - 30 Adaptive Force (based on level) when in the river.
May you be as swift as the rushing river and agile as a startled Rift Scuttler.Why?
Waterwalking empowers your ability to duel in the river for neutral objectives like Dragon and scuttle crabs.
