The answer is always karthus

Annie + Trist:

Passive: Spells gain increased attack range per level.

Q: Rapid Bombardment: Trannie's (Someone please make a better flowing name.. XD) Basic attacks have a 5-25% (Rank 1-5) chance of launching five fireballs at the enemy, striking them for 10-60 damage per fireball. (.3-5 AD scale)

W: Scorching Teleport: Trannie quickly teleports to target location, dealing 50-250 true damage upon arrival and leaving an AoE that deals 10-50 magic damage per second for five seconds to enemies within it. (25-20 second cooldown, enemy kills reduce the cooldown by 5-10 seconds.)

E: Molten Shot: Deals 50-1000 Physical damage over 12 seconds, reduces healing by 10% and gives Trannie a shield that builds in strength over 12 seconds absorbing up to 900 damage. (Shield scales with AP, damage scales with AD.)

R: Explosive Appearance!! Trannie's next attack within 20 seconds places a burning mark upon her target. Within five seconds Trannie then lobs an ignited log at her enemy causing (Insert summon name) to be brought forth for 30 seconds if it kills her target. (Deals 250-500 damage in a small AoE (Scales with both AD and AP.))

Zerokai.

Passive: Upon death, Zerokai spawns a gigantic thorn lash, which fires a massive thorn for true damage in a line upon cast of any ability, Zerokai is revived if the thorn strikes any targets, and any damage done is converted half and half into health and mana for Zerokai. This effect cannot happen more than once every 5 minutes.

Q: Ranged AoE Knock to the middle (Ala Orianna) Can activate W into a plant that can either run and attack at the targeted enemy then explode on impact, or drag W targeted enemy kicking and screaming (mobile snare effect) back towards the nearest unfriendly turret for 1.5 seconds and then explode.
W: Zerokai places a seedling either on the ground or on a targeted enemy, if placed on the ground the seedling will charge the nearest targeted enemy and attach itself, rooting them for a scaling duration. If placed on an enemy the seedling will blind them for 2 seconds and remain attached for another 13 seconds afterward.
E: Zerokai hurls heat seeking vines at an enemy (prioritizes champions) that will travel in a straight line after the first enemy is struck for the remainder of their length. Upon impact the vines slow enemies by 60% for 3 seconds. If the vines strike a ground seedling they will fire two more vines at 90 degree angles to the striking vine and cause a small explosion. If they vines strike an attached seedling, they knock the enemy to the end of their range, causing the seedling to explode upong impact with the ground.
R: Causes a large AoE thorn cage to grow, which snaps shut upon the second activation of R, dealing 25% of the damage dealt by enemy champions in the AoE to all enemy champions as magic damage, if the damage exceeds 25% of an enemy's total health, the enemy is dragged into the ground as the thorn cage collapses, becoming untargetable but also unable to take any action for 2 seconds.

LeBlanc + LeBlanc

bump

MF + Teemo.

The ultimate will effectively turn an entire lane into a mushroom minefield.

Darius+Karthus. Ult deals true damage to all enemies and refreshes on kill.