Here you can read up what he does. Super light summary in tl;dr section.
**The weapons: **
Aphelios has 5 weapons total.
He carries 2 weapons at a time, at all times.
Use W to switch between the 2 weapons.
Each weapon has 50 ammo.
Once ammo is depleted, Aphelios switches to a new weapon.
Throws a bomb forward, exploding on first enemy hit and damaging all nearby enemies. He then shoots all damaged enemies with an enhanced basic attack.
Q depends on weapon used.
P is for Passive.
R is for enhanced attack.
There is no E ability. E shows the next weapon in queue.
P: Increased attack range. Abilities _that use the rifle_ mark enemies. Basic attacks consume the mark on the target and all nearby enemies, dealing extra damage. This attack uses the other weapon and has unlimited range.
Q: Skillshot that damages and marks first enemy hit.
R: Applies an enhanced mark.
P: Heal for some damage the weapon does. Overhealing gives a shield.
Q: Rapidly attack the nearest enemy using both guns with reduced damage.
R: Flat heal.
P: Slows enemies.
Q: Root and damage slowed enemies.
R: Enhanced slow.
P: Higher damage. Hits enemies behind target.
Q: Shoots flames to do AoE damage. All targets hit are attacked with other weapon.
R: Hits all nearby enemies instead of behind them.
P: Throwing weapon. Can't attack until it returns. Attack speed increases travel speed. If used for abilities, creates a copy of itself for each enemy hit.
Q: Deploy a turret. Has same attack type as your other weapon.
R: If less than 3 enemies were hit, creates 3 copies of itself.
**Levelling up: **
Abilities level automatically.
Uses points to level stats instead.
Stats than can be leveled: Attack Damage, Attack Speed or **Bonus** Armor Penetration.
Switches weapon when out of ammo.
Rifle has range. Skillshot ability.
Pistol has lifesteal. Urgot W-like ability.
Cannon has slow. Root ability.
Flamethrower has AoE. AoE ability.
Boomerang is close ranged. Turret ability.
R shoots a bomb forward that explodes.
Levels stats instead of abilities.
That wraps it up folks!