Sentinel of Skydeep

Hexproof
If {r/g} was paid with {r}, Sentinel of Skydeep
has haste. Otherwise, it has trample.
Whenever Sentinel of Skydeep becomes blocked, tap all defending creatures.
Through the waves of Skydeep, sailors glimpse
the stone in it's head, and the next thing they
know, they've been led into a shipwreck.