Use hexes to slash R's CD. Take any R-CDR hex; Ultimate Revolution is even better.
Submitted by ARAMMayhem.com
About Malphite
About Eureka
More Eureka Combos
Veigar S Pairs with passive for massive AP and ability haste. 
Lux S Ethereal Weapon procs Lux's passive — E into multiple enemies and you can detonate the passive mark on all of them. Lux S Pure AP is squishy and damage-light — go half-tank and stack CDR for faster passive procs. Use R to clear waves. 
Karma S Play this when the enemy lineup is squishy. RQ for explosive damage. 
Trundle S R deals % magic damage — level 3 base is 30%, +16% at 800 AP, and 3500 AP hits 100% max HP. 
Maokai S Void Rift is magic damage, so it fits AP champions with high magic pen — % magic pen amplifies it, and Pridestalker's ability damage procs it many times. Forge: magic pen > AP > MS. 
Ekko S At 500 ability haste, R has only a 12s cooldown. 
Syndra S Syndra's QE triggers Slap Around twice; hitting multiple enemies stacks it extra fast. Keep exploring
Malphite + Eureka ARAM: Mayhem Combo Guide
This S-tier combo pairs Malphite with Eureka in ARAM: Mayhem. This is one of the strongest combos available — pick it whenever you can.
Use hexes to slash R's CD. Take any R-CDR hex; Ultimate Revolution is even better.