Grakren, Seafloor Tyrant

Trample
Grakren, Seafloor Tyrant can't attack unless you control 10 or more islands.
Whenever Grakren, Seafloor Tyrant attacks, gain control of all islands.
Islands you control have "{t}: Add {u}{u}."
{1}{u}, {t}: Search your library for an island card, put it onto the battlefield tapped, then shuffle your library.