Naxeroth, Titan's Herald

Vigilance, First Strike
Colorless spells you cast cost {2} less to cast. If that
spell is Legendary, it costs {4} less to cast and gains protection from instants until end of turn.
Other legendary permanents you control have
hexproof as long as they are not attacking.
When a legendary permanent leaves the battlefield,
place it on the top of your library instead.