Nessie, Legend of Loch Ness

Hexproof, Island walk, Double strike
When you cast this spell, {x} target lands become islands in addition to their other types for as long
as this creature remains on the battlefield under
your control where {x} is the amount of {g}
used to cast it.
Other blue spells you control cost {2} less to cast
Other green creatures you control have ({t}; add {c}{g})