Lane sustain, money stacking, and lane trading.
Creative tools and rule bending
Your first 2 attacks after using an ability on champions grants gold and sometimes consumables.
Gain a free stopwatch. Stopwatch has a one time use Stasis active.
Get a free biscuit every 3 minutes, until 12 minutes. Biscuits heal and permanently increase your max mana.
+5% Max CDR
+5% Summoner Spell CDR
+5% Item CDR
Durability and crowd control
Heals and shields are 5% stronger and increased by an additional 10% on targets below 40% health.
Restore health over time based on your missing health.
+5 Armor or 6 MR (match-up)
Gangplank is one of the biggest abusers of Kleptomancy thanks to his on-hit [Q]. Klepto will provide you with a ton of sustain/gold and occasionally more AD.
Perfect Timing is a great rune when looking to get an early/cheaper Guardian Angel.
If you find yourself in a tough lane matchup and think you'll need more sustain, take Biscuit Delivery here instead.
Biscuit Delivery is great for land poke and trading with [Q] early in the game. The extra bit of mana is also nice to keep you topped off to whittle away your opponent.
More CDR means more [Q]s which means for Klepto procs which means more gold... You get the idea.
Revitalize empowers your [W] healing for additional sustain and protecting from major lane harass damage before you're able to scale.
Second Wind's mid-fight health sustain doubles down on your ability to trade as a bruiser with your lane opponent, meanwhile stacking gold with Klepto for the accelerated item powerspikes.