How would you make YOUR main overpowered? Here's what I would do (Veigar)
Inspired from MagicScumpy's making x melee character overpowered series on youtube
Veigar, The Tiny Master of Evil
Level 1 HP: 493 HPp5: 5.42 Mana: 392 Mp5: 6 AD: 50.7 Attack Speed: .625 (+38.1%) Armor: 22.6 MR: 30 MS: 355 Range type: (Ranged) Range: 650
Level 18 HP: 1887 HPp5: 14.8 Mana: 1276 Mp5: 19.6 AD: 95.3 Attack Speed: .863 Armor: 86.3 MR: 30 MS: 355 Range type: (Ranged) Range: 650
Passive: Evil Power:
Phenomenal Evil Power: Veigar is the greatest evil to ever walk Valoran and he's only getting bigger! Veigar gains 1 stack of Phenomenal Evil Power every time he strikes an enemy champion with an ability and gains 5 on champion takedowns. Veigar gains 1 ability power for every stack of Phenomenal Evil Power.
Perfect Phenomenal Evil Power: Every time Veigar kills an enemy champion with Primordial Burst he devours a portion of their soul gaining 1 stack of Perfect Phenomenal Evil Power. Veigar gains 1% bonus ability power and 1% bonus mana for every stack of Perfect Phenomenal Evil Power.
Q: Baleful Strike: Veigar fires a bolt of dark energy in a target direction striking 1/1/2/2/3 targets dealing 30/80/130/180/230 + 60% ap ratio + 5% mana ratio magic damage to the first target hit and 50/100/150/200/250 + 70% ap ratio + 5% mana ratio magic damage plus 1/2/3/4/5% enemy max health ratio true damage to all subsequent targets if the first target hit with Baleful strike is slain. Killing an enemy unit with Baleful Strike grants Veigar 1/2/3/4/5% movement speed and an extra .01 for every stack of Phenomenal Evil Power he has for 1 second or 2 seconds if the target killed was a large minion, monster, or enemy champion. Killing a target also grants 1 stack of Phenomenal Evil Power or 2 stacks of if the target killed is a large minion, monster, or enemy champion. If Baleful Strike kills more than 1 target all targets killed after the first one may grant Veigar 1 bonus mana or 2 bonus mana if the killed target is a large minion, monster, or enemy champion. Killing a target also reduces the cooldown of Baleful Strike by 1/1/2/2/3 seconds or 2/2/4/4/6 seconds if the killed target was a large minion, monster, or enemy champion.
Damage to first target: 30/80/130/180/230 + 70% ap ratio + 5% mana ratio magic damage Damage to further targets: 50/100/150/200/250 + 70% ap ratio + 5% mana ratio magic damage + 1/2/3/4/5% enemy max health ratio true damage Phenomenal Evil gained: small minions, small monsters, and small pets: 1 large minions, large monsters, large pets, and enemy champions: 2 Bonus Mana gained from killing multiple targets: small minions, small monsters, and small pets: 1 large minions, large monsters, large pets, and enemy champions: 2 Movement speed for killing a target: 1/2/3/4/5% + .01 per stack of Phenomenal Evil Movement speed duration: small minions, small monsters, and small pets: 1 second large minions, large monsters, large pets, and enemy champions: 2 seconds Mana cost: 60 Cooldown: 16/14/12/10/8 seconds
W: Dark Matter: Veigar commands a meteor to fall at a target location after 1.6/1.35/1.1/.85/.6 seconds dealing 100/140/180/220/260 + 100% ap ratio + 1% mana ratio magic damage and slowing all targets struck by 10/11.25/12.5/13.75/15% plus an extra .01 for every stack of Phenomenal Evil Power he has, for .5 seconds plus and extra .0002 seconds for every stack of Phenomenal Evil Power he has. All targets killed by Dark Matter drop disintigrated husks of their soul on the ground which Veigar can pick crush in his gauntlet to heal himself for 5/10/15/20/25 + 2-19% missing health ratio (based on Veigar's level) and refunding 4/8/12/16/20 mana or 50/75/100/125/150 + 2-19% missing health ratio (based on Veigar's level) and refunding 4/8/12/16/20% missing mana ratio mana if the devoured soul was the soul of an enemy champion or epic monster. Souls of minions and monsters last for 5 seconds and the souls of enemy champions and epic monsters last for double the duration. However for the .4 seconds Veigar is crushing the soul he cannot cast Baleful Strike, Dark Matter, or Primordial Burst. His movement remains unhindered though. After Veigar has finished crushing a soul husk all soul husks currently on the ground disapear out of fear. Veigar can select which husk he wishes to crush if there are multiple by clicking on the desired soul husk. Any ability or crowd control effect that interupts channels also interupts the process of Veigar crushing a soul husk. Crushing a Soul always grants Veigar 1 stack of Phenomenal Evil Power. While crushing a soul Veigar gains 1/1.5/2/2.5/3% + .01% ,for every stack of Phenomenal Evil Power Veigar has, damage reduction for the .4 second duration.
Damage: 100/140/180/220/260 + 100% ap ratio + 1% mana ratio magic damage Slow: 10/11.25/12.5/13.75/15% + .01 for every stack of Phenomenal Evil Power Duration: .5 seconds + .0002 for every stack of Phenomenal Evil Power Soul Crush partial channel duration: .4 seconds Heal Amount: Regular Soul Husk: 5/10/15/20/25 + 2-19% (based on Veigar's level) missing health Champion/Epic Monster Soul Husk: 50/100/150/200/250 + 2-19% (based on Veigar's level) missing health Mana Refunded: Regular Soul Husk: 4/8/12/16/20 mana Champion/Epic Monster Soul Husk: 4/8/12/16/20% missing mana ratio mana Phenomenal Evil Power gained through crushing a Soul Husk: 1 Stack Damage Reduction: 1/1.5/2/2.5/3% + .01% per Phenomenal Evil Power Stack amount Delay: 1.6/1.35/1.1/.85/.6 Mana Cost: 100 Cooldown: 20 seconds
E1: Event Horizon: After a .75/.65/.55/.45/.35 second delay Veigar summones a hexagonal cage which knocks down, grounds targets inside, and stuns all targets who touch the walls for 1.5/1.75/2/2.25/2.5 seconds. All movement abilities are cancelled upon contact with the walls before the target is stunned. The walls remain for 3 seconds. While event horizon is on cooldown Veigar may activate his E2.
Stun duration: 1.5/1.75/2/2.25/2.5 seconds Cage duration: 3 seconds Cage Delay: .75/.65/.55/.45/.35
E2: Megaparsec: Veigar slowly teleports to a target location leaving after-images and becoming untargettable over .5 seconds.
E Passive: Megaparsec cools down twice as fast while Event Horizon is off cooldown.
Range: 650 Teleport/Untargettable duration: .5 seconds Mana Cost: 80 Cooldown: 80/75/70/65/60 seconds
R: Primordial Burst: Veigar blasts a target enemy champion dealing 175/250/325 + 75% ap ratio + 10% mana ratio magic damage. If the target is killed by Primordial Burst Veigar gains 1 stack of Perfect Phenomenal Evil Power. Primordial Burst deals 1.5% increased damage for every 1% of the target's missing health, up to double damage against targets below 33.3% of their maximum health. If Primordial Burst kills a target the remaining damage that exceeded their health bar is dealt to every enemy champion within 750/875/1000 range as overkill damage. If any enemy champions are killed by this overkill damage Veigar gains 1 Stack of Perfect Phenomenal Evil Power and the overkill damage continues until no further targets are located.
R passive: If Primordial Burst was cast on an enemy and was blocked (did 0 damage) the energy disperses and reforms in Veigar's hand refreshing its cooldown completely.
base AA range: 700
Passive: Night Hunter: Vayne gains 50 movement speed towards enemy champions.
Q: Tumble (Cooldown: 5/4/3/2/1 seconds)
Vayne tumbles forward, gaining 100 basic attack range and dealing 70/80/90/100/110% of her AD as bonus physical damage on her next auto attack.
W: Silver Bolts:
Every 3rd basic attack on a target does 5/10/20/25/30% + (8% per 100 AP) of the target's maximum health as bonus true damage. Stacks do not fall off when switching targets.
E: Condemn:
Vayne shoots a piercing arrow at the target, dealing 100/150/200/250/300 + (90% AD) + (80% AP) bonus physical damage and knocking them back a short distance. If the target collides with a wall, they're stunned for 3.5 seconds and the damage critically strikes for 200% damage (scaling with Critical Strike Damage).
R: Final Hour:
Vayne goes into god mode, becoming completely immune to all damage and crowd control and gaining 50/75/100 AD. During this time, she gains 200 extra auto attack range, tumble stealths for 8 seconds, silver bolts does double damage, condemn deals 50% of the target's missing health as bonus magic damage (still doubled when in contact with a wall), and night hunter's bonus movement speed is quintupled.
P: landing spells on enemy champions heal you for 5% of your missing health and restores 5% of your missing mana as well as cause chogath to enrage
While enrage chogath's abilities gain extra range and he has a 200% movespeed buff for 2 secs
with his w make it to where the linked ally gets the unique passives he has on him
Make her W instant instead of a 1.5 delay :')
Passive: Since they're doing the whole magic damage marksman type of thing with Corki, I would enable his auto-attacks to build not only with attack damage but with ability power as well. Making him an attack damage, and ability power hybrid.