Power Boots
From Inkipedia, the Splatoon wiki
The Power Boots are shoes in Splatoon. It is 2-star rarity obtained through the Inkling Squid amiibo.
Its ability is Ink Saver (Main) which decreases amount of ink consumed by your main weapon.
Unlock
Complete these 4 missions the Amiibo gives you to unlock it:
Appearance
Abilities
The Power Boots come with the Ink Saver (Main) ability as a main ability.