Potions heal for a small amount instantly and you move faster while being healed by them.
Offense
+1-10% CDR
Flex
+6 Armor or 8 MR (match-up)
Defense
+6 Armor or 8 MR (match-up)
WhyGrasp of the Undying
Grasp can easily be procced by Gangplank from range with [Q] poke ([Q] acts as an auto-attack). The extra damage and heal allows you to out-sustain your lane opponent.
WhyDemolish
Demolish on Gangplank when paired with his passive makes you a split-push tower taking monster.
WhySecond Wind
Second Wind, like Bone Plating, is great for helping you to absorb incoming lane harass damage in tough matchups.
WhyRevitalize
Revitalize synergizes well with the healing from both Grasp and [W] to keep your lane sustain quite high so you can power-farm for items in tough matchups.
WhyBiscuit Delivery
Biscuit Delivery empowers your early laning phase to help you ssutain and scale into your Tri-Force completion.
WhyTime Warp Tonic
Time Warp Tonic pairs well with Corrupting Potion to further empower your early trading and lane sustain.