Augment, item and mechanic interactions most players miss in ARAM: Mayhem.
With Jhin's 
Dancing GrenadeQ or Teemo's 
Blinding DartQ, the 2 extra shots of 
Tripleshot can fly very far behind the target. Tip: cast it on the minion at the back, and the 2 extra shots fly straight into the enemy team from a distance nobody expects.
With Karthus's 
RequiemR or Ashe's 
Enchanted Crystal ArrowR, 
From Downtown calls down giant meteors like Ziggs's ultimate. The downside: the meteors fall rather slowly.
Unlimited health stacking, growing bigger after every takedown, and executing low-health enemies. These three augments turn a tank into the one carrying the team.
Ethereal Weapon makes abilities apply on-hit effects, so they also trigger the cooldown reduction of 
Mystic Punch. Every ability that lands cuts your cooldowns further.
Steel Your Heart triples your Heartsteel stacks, and 
Stackosaurus Rex grants 100% extra permanent stacks. Together, your health grows exponentially.
Atma's Reckoning gives 20% Critical Strike Chance and up to 30% more based on bonus health. Health-stacking fighters with 
Jeweled Gauntlet are both tanky and crit with their abilities nonstop.
Rite of Ruin gives 55 Ability Power and 25% Critical Strike Chance, plus up to 20% more crit for each ability you cast. With Jeweled Gauntlet, abilities can crit, and mages have almost no other source of crit.
Turn on 
Lightning Field / Hyper ChargeW in cannon form before your 
To the Skies! / Shock BlastQ + 
Thundering Blow / Acceleration GateE combo. 
Purist - Caster converts the attack speed from W into Ability Haste, so your cooldowns drop massively.
Javelin Toss / TakedownQ deals more damage the farther it flies. With 
Spell Split, the split spears keep the distance already traveled, so they hit as hard as the main one.
Shield VaultW deals damage based on Pantheon's max health. Stack enough health with Tank Engine and Steel Your Heart, and one W can deal damage equal to the target's entire max health, or more.
Tongue LashQ grows as Tahm Kench grows, so 
Goliath and Tank Engine fit him perfectly. With Ethereal Weapon too, rush 
Dusk and Dawn: one Q can add up to 3 passive stacks, plus damage and healing.
While swinging with 
Spin Me Right Round, every automatic attack applies on-hit effects. AP Volibear with this augment and 
Statikk Shiv swings around firing lightning nonstop, dealing huge damage in a moment.
Both Statikk Shiv and Dusk and Dawn proc on hit. That is why champions that fit Ethereal Weapon often build these two: every ability that lands also brings the item damage.
Purist - Caster cuts cooldowns by a percentage, counted separately from normal Ability Haste. That is why many endless-ult builds need both: very high Ability Haste and Purist - Caster.
Overlord's Bloodmail turns max health into attack damage. The more health you stack with Tank Engine or Steel Your Heart, the harder every attack and ability hits: Sett can wipe a health bar with one punch.
