All "Gravekeeper's" monsters gain 500 ATK and DEF. Cards in either player's Graveyard cannot be banished. Negate any card effect that would move a card in the Graveyard, other than itself, to a different place.
Stop throwing wrong informations.
Necrovalley never banned in OCG or TCG, actually Konami errata it so it's became stronger in OCG.
Also, many GK Cards mention this field card and Ishatar uses it so it's just a matter of time until we get this card (I believe they will release it in Card Trader and not a reward)
It says "Negate card effects that move a card from the graveyard, other than itself, to a different place"
Phoenix moves itself out of the graveyard. Hence it can resummon itself easy and destroy Necrovalley.
You need 3 copies of both Soul Exchange and Double Summon so I'm not sure how that's very f2p friendly. Not to mention that Ice Barriers, Mill, Toons, and Naturias are cheap as hell, and even Phoenix isn't that expensive, although you'd probably have to make it a little less optimal than you'd like.
Necrovalley is just crazy, 500 atk and def plus all the gravekeeper effect activated, and prevent graveyard play. A legendary ocean is in a different level, it's not too op. But I agree about amazoness village, they should already added as mai level up reward long long time ago.