...To understand, at least. He will take practice to get accustomed to playing him, I'll grant that.
I will attempt to make Aphelios' kit as simple and straightforward as I can.
**Passive**: he gains stats instead of skill points when he levels up. Simple enough.
**W**: Switch to your other weapon.
**E**: Does not exist.
**R**: It's a bomb.
**Weapon 1 (Calibrum)**: It shoots farther. Click marked things to hurt them with your other gun.
Calibrum Q: A skillshot that marks things.
Calibrum R: Consumed marks hurt more.
**Weapon 2 (Severum)**: It heals you a little. Gives a little shield if you're full.
Severum Q: Move faster and shoot a bunch with both guns, for less damage.
Severum R: You get healed.
**Weapon 3 (Gravitum)**: It makes enemies slower.
Gravitum Q: That slow suddenly becomes a root.
Gravitum R: That slow is a bigger slow.
**Weapon 4 (Infernum)**: This is a flammenwerfer. It werfs flammen. (It leaves a painful area behind enemies.)
Infernum Q: A wave of fire, then shoot with your other gun.
Infernum R: Creates a painful area around enemies instead of behind them.
**Weapon 5 (Crescendum)**: You can attack again when this gets back to you. Crescendum does more damage if it's your other gun.
Crescendum Q: Your other gun becomes a little friend.
Crescendum R: We'll pretend like you hit three enemies for doing more damage, even if you didn't.
The only other thing to understand is that a weapon will move to the end of the line once 50 Moonlight has been used up.
**_CONCLUSION_**: Think of it as Apehlios having five 'mini-kits'. That's a lot of mini-kits, but none of them are particularly complicated. The intricacies come in Moonlight management to make the next gun-pairing one with good synergy.