For example, 
Sweeping Blade temporaily gains AD scaling and 40/50/75% on target CDR
So, lots and lots of dashing (instead of 6 sec at max rank, you only need like 1.25 seconds to dash on the same target)
Try to be creative, increasing damage is fine, but just adding +9999 damage is a low hanging fruit
Q: Steals opponents money.
W: Eats an orange and is k.
E: Turns into a barrel and barrel rolls the enemy.
Q: Permabans enemies hit
W: Dragon pit sized area of damage
E: Yeah they're not breaking it with a spell that's for sure
Veigar's Dark Matter now scales with enemy HP.
My contribution:
Riot's contribution:
Q: Garen becomes invulnerable to CC, and goes at %65 bonus movespeed
W: Duration halved, becomes invincible for the duration
E: Spins so fast that he becomes a helicopter and flies out of the game
Q: deals %HP True damage on hit + breaks armor for extended time
W: now creates an explosive clone, that deals extra magic damage (scales with AD) and knocks up if not destroyed
E: range is extended and now creates 5 clones instead of 2. attack speed is increased by 90% for a few seconds.
Mini Q: Now goes Global with 3x damage. Mega Q: Now stuns with a larger AoE. Mini W: For 60 seconds, it stuns after 3 hits. Mega W: Larger AoE, stuns for longer. Mini E: Automatically hops 3 times, can hop infinitely if it hits units. Mega E: Roots everyone in a 2x larger area.
Q: now also deals 75% splash damage. W: gives shield to all allies in 1000 range, can deal up to 5 times the damage E: deals up to 150% increased dmg and roots for up to 1.5 seconds (scales with how close your enemy is, the closer he is, the bigger damage and root).
Q: creates a big turret
W: fires multiple waves of missiles
E: throws three grenades
R: upgrades a spell
Annie ult now deals 10349 base damage.
Q: Damage increased and stuns all targets hit.
W: Range doubled, draws all enemies hit toward his current position, stunning them.
E: Now bounces like ziggs bombs, Increasing range(from blue side red buff to Dragon pit entrance on first bounce, blue side red buff to red side blue buff with all bounces(at max rank)) champions hit are absorbed by the blob and carried to final destination. No increase to damage, but increase to stun duration to targets hit on first and second bounces, final bounce knock up is the same as E with no upgrade.
Q: Increased size of AOE, now spawns Tri-spitters which attack upto 3 targets at once
W: Spawns 5 seeds in a cross pattern
E: Becomes an AOE centered on Zyra, now spawns Grapplthorns which pull targets hit a short distance toward the plant.
E: every hit now knocks up and stuns targets hit for 1/1.5/2 seconds Q: In addition to its current effects, this also fires three Depth Charges in a line in front of him, knocking up and stunning enemies hit W: While active, Nautilus will fire a depth charge at his current location, knocking up and stunning enemies close to him
Q becomes a 3 charge stealth/flash
W mega box that fires missiles and blows up at death or end of duration
E throws 2 shivs that stick into the enemy and cause a bleed effect if shaco pulls them out. Imagine kalista rend only must be pulled out by a melee attack.
R well, if you could upgrade it, i would say let the clone actually listen to you and not stand there once you die. Or just spawn 4 or so clones that run in random direction and blow up on enemies doing the normal aoe damage.
's abilities already upgrade so uhh..
Q: Deals 30% more damage to champions, AOE size increased, the extra damage done is true damage. (Stacks with her passive upgrade)
W: Slow intensity increased, will deal a second wave of damage and knocks-up all enemies still within the AOE after a second or so.
E: 360 degree knock-away that "flings" enemies a short distance beyond the AOE and knocks all sphere back further with perhaps a bit more damage.
R (Because why not hehe): Balls will deal splash damage around the target with increased range.
Veigar: Q=Bounces between enemies, ramping up damage as it does so. Bounces up to 5 times for the 5th hit to deal 400% of its base damage. W= Increased range. Summons Michael Bay himself to act like a super minion. E=Stun doubled. No delay between cast and spell going up, and the stun affects everyone in it instead of just the edges. Tahm Kench: Q=Tongue wraps around the enemy, dealing bonus damage and pulling them to Tahm. Increased range. Once they are pulled they acquire 3 stacks of An Acquired Taste. W=Inhales to eat enemies in a cone. Once they are eaten, Tahm cannot move, but gains a heal based on the damage going on to the enemies inside him. E=Tahm converts all grey health into real health, and gains a movement speed boost. While the boost is up, he is immune to CC effects and can eat enemy champions without being slowed. Cassiopeia: Q=Global poison damage. Deals 2x the current base damage of Q poison per second for 3 seconds. W=Poison cloud is doubled in size and deals standard poison damage. Enemies inside it are slowed by 60% and lose vision of allies. E=Fires 5 times in succession, and if it kills a unit, Cass gains 15 stacks and her Q, W and E cooldowns are refreshed.
q: immediately gets passive and heals you
W: summon 3 more fox fires and have them deal TRUE damage
e: enemy champion is forever in love with you, and you can use him like Morde ult (not op at all right)
Q: Larger AOE, stuns for half a second after knockback.
W: Roots all enemies near the target.
E: Sapling has greatly increased speed and damage and ignores minions.
Q: More damage, longer knockup, does not stop on champion collision.
W: Larger AOE, now slows. If E is activated during the slow, the slow is extended.
E: Now stuns instead of slowing.
Q: Now shoots through all units it passes through, and has a 100% AP Ratio. W: Now drops meteors around Veigar passively, much like his Doom Bots counterpart for 10 seconds. When used as a cast, has a 0.5 second delay before 3 meteors drop down consecutively. E: Becomes instant, and sucks those that are inside the cage toward the edges. Damage becomes amplified if they are stunned.
Q: Terrifies all nearby enemy Champions
W: Drains chains from the first target to nearby secondary targets
E: Crow bounces twice as many times, and can hit bounce back to the same target without stopping
His next Q does double damage and strikes in an AOE the size of an Ekko ult.
Yasuo: Q- is now a wayy bigger tornado W- is a complete circle around him that expands forward and hurts enemies that pass through it E- after 5 seconds every target you've dashed through takes chain lightning damage
Q: Enemies hit by Transfusion are now bleeding out and take 50% of his total AP plus 10% of their maximum health in true damage, as well as being slowed, for the course of 3 seconds.
W: Vladimir can move through terrain while in his Sanguine Pool. He cannot take any damage while in his pool and enemies in it for more than 1 second are rooted.
E: At 4 stacks, Tides of Blood deals true damage, slows enemies hit, and also can hit allies in order to heal them and give them increased damage on their abilities.
Q: The whirlwind deals true damage, as well as slowing enemies for 2 seconds after being knocked up while taking 10% of their max health in true damage over the course of those 2 seconds.
W: Enemies cannot move through Windwall, but if Yasuo passes through it, instantly has 2 stacks of Steel Tempest and has it off of cool down and has full Flow.
E: The cool down on enemies for Sweeping Dash is reduced to 5 seconds. Any enemy who has recently been hit by Sweeping Dash takes true damage from Yasuo.
Q: Now deals true damage to the first enemy hit, slows them by 30%, and has them bleed for 2 seconds taking 10% of their max health in physical damage. Enemies hit by more than one Razor Shuriken will only have half of the damage applied for the second (or third) shurikens and will have their armor reduced by 25 for three seconds.
W: Zed's shadow can be moved like a Shaco clone, can auto attack doing %maxhealth true damage, procs his passive, and has no range on switching with it.
E: True damage. Slows. No energy cost.
q: ring of shurikens shoots out from zed and then returns to him after a few seconds
w: zed can infinitely switch places with his shadow until the shadow expires
e: Zed spins like garen 5 times and every spin zed will do his e's damage and stuns
Q: Stuns enemies even if it doesn't double up and slows afterwards
W: Doesn't need to power up and if an enemy goes over them then they take damage
E: Enemies can't get through, that is all
Q: Knocks up with each hit
W: 
Tons of damage
E: Larger range and stuns rather than slows
This is fun...
Q: Two additional orbs fire, creating a large X pattern
W: Zone continuously pulls Champions towards the center of the pool, dealing increasingly high damage over time
E: Automatically spreads to nearby units after 2 seconds.
Q: Shoots out a wave of ruptures( like in doom bots) and instead of slowing, it stuns for 2 seconds.
W: Scream is in a area around him, with increased range. Also, damage is increased.
E: Pressing E after R causes Cho's next 5 AA to shoot out enhanced vorpal spines. dealing massively increased damage, and slowing everyone hit by 80% for 1 second.
After making this, I really want to play cho like this, lol.
Q - Now spawns multiple spheres in rapid succession. W - Can now pick up an enemy champion, throw range greatly reduced from where the champion was picked up. E - Now 360 and will fire off the spheres that float around her for a stun.
Q: Builds up charges so you can cast two quickly
W: For each point in Upgrade, gain an additional bubble
E: Pulls all targets marked by q to you.
Q: Think Garen spin
W: Now applies to 2 auto attacks
E: Enemies grabbed are now immobilized for 2 seconds.
Q: Range increased to 3000/3500/4000, AoE Radius increased by 100/150/200%, Damage increased by 40/60/80%, Now knocks up in all of the area of effect
W: The next strike's healing procs "Blood Savagery", giving Aatrox maximum attack speed and making all of his attacks proc the current toggle. This lasts for 6/7/8 seconds
E: Range and size increased by 100/175/250%, Damage increased by 25/50/75%, Is now instant and deals damage in between the two skill blade edges as well
Q: Damage increased by 15/20/25%, now divides in 8/12/16 different directions, secondary bolts now also divide into double the previous amount at maximum range
W: Is now a global, Projectile Speed increased by 125/175/225%, Can now be detonated at any time, Damage increased by 30/50/70%
E: AoE Radius increased by 150/200/250%, Knock Up duration increased by 0.5/0.75/1 second(s), Now applies two stacks of passive
Q: Is now piercing, Damage increased by 50/75/100%, Devour now eats every minion hit and will spit them out for 30/35/40% additional damage for every minion swallowed past the first
W: No longer requires 3 stacks of passive to eat enemy champion, damage increased by 20/35/50%, can be cast a second time before the first enemy champion exits Tahm's belly
E: Shield now lasts for 50/75/100% increased duration, no longer decays, shield now instead regenerates by 5/7.5/10% the current shield value per second
Q: Is now targeted but still deals damage to enemies in hit on the way, damage increased by 45/60/75%, now stuns instead of slows
W: Now creates Sand General that lasts infinitely, a maximum of 1/2/3 sand generals can be alive at the same time, damage increased by 5/10/15%
E: Can be recast up to 3/4/5 times within the next 8/11/14 seconds, shield value increased by 50/75/100%, now damages enemies by 40/50/60% of the shield value
Q: Stack damage is increased by 75/100/125%, Cool Down is reduced to 1 second, Stacks gained from this attack is increased by 300/400/500%
W: Duration increased by 50/75/100% (still reaches max at the normal time), removed mana cost, now also stuns the enemy every 2.5 seconds for 0.25/0.5/0.75 seconds
E: AoE Radius increased by 200/300/400%, Armor Reduction increased by 50/75/100%, Range is now global
Q: must stronger knockup in a larger radius, does much more damage
W: AAing him during this does % max hp magic damage as well as the base and armor scaling
E: Target is taunted for 2x current duration of current ability, and 20% more damage from all sources.
Q: Now automatically gives Draven 2 Spinning Axes. In addition, if an Spinning Axe lands on an enemy unit, it deals damage to that unit and bounces again.
W: Lasts for twice as long, building up speed over the duration. All enemy and allied Champions close to Draven are Charmed.
E: Throws two out that spin around him a few times. (this one kinda sucks sorry)
