Given how many times Krakoa has been invaded I figured we can come up with a plethora of mutant protocols that could protect the Island.
Protocol#1: Illusion death barrier
Number of mutants required: 12
Illusion:
Mastermind
Lady Mastermind
Martinque Jason
Intoxicants:
Pixie
Beautiful Dreamer
Wind Current:
Storm
Wind Dancer
Transmutation:
Alchemy
Chrome
Magnekinesis:
Magneto
Polaris
Momentum:
Harry Leland
The Illusionist project around the island while Pixie and Beautiful dreamers intoxicants aide the potency. It should be strong enough to affect the Sentry. Storm and Wind Dancer are in charge of making sure the dust shield doesn't affect Krakoas inhabitants. Also to open exit points.
Chrome and Alchemy transmute boulders into adamantium. And Magneto and Polaris shape them into Daggers and fling them at people. Harry Leland increases the mass of the objects flung for maximum impact.