All about the all-in. FLASHy engages. AP burst.
Creative tools and rule bending
Get Summoner Shards and exchange them at the shop to change your Summoner Spells during game.
Gain a free stopwatch. Stopwatch has a one time use Stasis active.
You can enter debt to buy items.
+5% Max CDR
+5% Summoner Spell CDR
+5% Item CDR
+20% Potion and Elixir Duration
+22 Ability Power or +13 Attack Damage, Adaptive
Gain cooldown reduction and max cooldown reduction on your ultimate. This is increased further each time you use your ultimate, up to a maximum.
Gain 4% extra MS. Gain extra AP or AD, based on your bonus MS, Adaptive.
This build is ALL ABOUT flashing in with your ultimate and blowing people up. The 25% summoner CDR + Cosmic Insight puts Flash on a 180s cooldown.
Spellbook also allows you take ignite in situations where you think you can all-in with Flash->[R]->Protobelt to secure the kill, while still having TP for late game.
Perfect Timing gives you the safety of a large 5-man Flash->[R] without having to worry about getting blown up.
Save the broken Stopwatch and turn it into a Zhonya's in the late game.
Get ahead with all-in kills and push your lead with earlier item power-spikes.
Use your debt spending wisely on big purchase completions. Don't go into debt on every single buy.
More Summoner CDR means more Flash all-ins.
More Item CDR means more Protobelt activations (which you should be rushing as your first item.
Kennen is all about his [R], and this loadout in particular places heavy emphasis on spamming [R] and abusing your low Summoner cooldowns to take big teamfights immediately.
Celerity actually synergizes incredibly well with Kennen's kit. The bonus Movement Speed from [E] grants you a burst of extra Ability Power during your [R] all-ins.