At one point in time, Flash had a rough jungle clear, mana problems, and all of that. Nowadays, in the age of amplifiers, things have changed. While his early ganks are still weaker than you'd hope for from your jungle, he's all about the late game. So long as you don't feed, and help your team secure objectives, you'll be able to hit your power spike, which is significantly earlier than it used to be. In fact, Flash is probably the most overpowered champion in the game right now, and only sliiiightly more difficult to play than Shazam.


Amps: Blaster: Early Burst no exceptions ever, ever, ever.


Skill Order: In the new age of amplifiers, Nil Ring start makes Q better than W in the jungle. W second, obvious reasons. I prefer passive > E, it's a damage amplification. E last. E is good, but good enough that one point will carry you.


Item Order: Rush Cosmic 4, since you have the mod, otherwise it would be Cosmic 3. Flat power pen is silly silly strong, and as soon as you get Cosmic Staff 4, you start doing pretty high damage. After Cosmic, Starheart, because it's all about the damage for Flash. After Starheart, Blue Scarab. Blue Scarab works on W, effectively increasing it's ratio by 10%. It also stacks a flat power pen debuff, incredibly quickly with W. Neron's is an obvious choice, Q W R Neron's, Q back out. Psi-Scim isn't what it used to be, but you're essentially an auto attacker at this point, and it's a further source of damage. Psi, Scarab, and W are a combined 50+10+30, 90% power damage on a single melee. Then (10+30)3 for the rest of W.

Final slot can be anything from that optional items section, depending on the situation.