Waterfall Temple3U
Enchantment - Dungeon
When Waterfall Temple enters the battlefield, target player puts a 3/2 blue Drake creature token with Flying onto the battlefield. Then if that player is you or your teammate, sacrifice Waterfall Temple.
Whenever one or more creatures you control deal combat damage to an opponent, transform Waterfall Temple.
-- Mindstealer Idol
Legendary Artifact
Whenever Mindstealer Idol becomes transformed, gain control of target creature for as long as you control this permanent.
Sanctum of the Ancients3GG
Enchantment - Dungeon
When Sanctum of the Ancients enters the battlefield, target player puts a 5/5 green Elemental creature token onto the battlefield. Then if that player is you or your teammate, sacrifice Sanctum of the Ancients.
Whenever you attack with creatures with total power 6 or more, transform Sanctum of the Ancients.
-- Relic of Might
Legendary Artifact
Creatures you control have +2/+2 and Trample.
Halls of WarRR
Enchantment - Dungeon
When Halls of War enters the battlefield, target player puts two 1/1 red Goblin creature tokens onto the battlefield. Then if that player is you or your teammate, sacrifice Halls of War.
Whenever you attack with 3 or more creatures, transform Halls of War.
-- Head of the First Goblin King
Legendary Artifact T: Target creature gets +3/+1 and gains haste until end of turn.
Crypt of Wails2B
Enchantment - Dungeon
When Crypt of Wails enters the battlefield, target player puts a 1/3 black Scorpion creature token with Deathtouch onto the battlefield. Then if that player is you or your teammate, sacrifice Crypt of Wails.
Whenever you attack with a creature with Deathtouch or Lifelink, transform Crypt of Wails.
-- Psychephage Scepter
Legendary Artifact B, T: Target opponent discards a card. Activate this ability only on your turn.
Maze of Silence3WW
Enchantment - Dungeon
When Grove of Silence enters the battlefield, target player puts three 1/1 white Spirit creature tokens with Flying onto the battlefield. Then if that player is you or your teammate, sacrifice Maze of Silence.
Tap four untapped creatures you control: Transform Maze of Silence. Activate this ability only on your turn.
-- The Final Whisperstone
Legendary Artifact
When The Final Whisperstone becomes transformed, exile target card in a graveyard.
Each opponent can't cast a spell that shares its name with a card in exile.
Each creature an opponent controls can't attack or block if it shares its name with a card in exile.
it seems quite complicated even though the idea is pretty simple.
if you remove the whole rigmarole of "target player puts a creature into play. if that player is you or a teammate, sac this card" and possibly remove a CMC from each card, it'd probably be a lot more elegant.
You are totally right. The flavor was supposed to be "you form a link to a dungeon by swearing to protect its secret (so the guardian is your friend) or try to steal its relic (so the guardian becomes your enemy)". I added the combat trigger and legendary artifact side to better reflect the second part. But it got too complex.
Improved version:
Waterfall Temple3U
Enchantment (R)
When Waterfall Temple enters the battlefield, target player puts a 3/3 blue Drake creature token with flying onto the battlefield, then sacrifice Waterfall Temple unless that player is your opponent. U: Gain control of target creature for as long as you control Waterfall Temple. Activate this ability as a sorcery, and only once.
Enchantment - Dungeon
When Waterfall Temple enters the battlefield, target player puts a 3/2 blue Drake creature token with Flying onto the battlefield. Then if that player is you or your teammate, sacrifice Waterfall Temple.
Whenever one or more creatures you control deal combat damage to an opponent, transform Waterfall Temple.
--
Mindstealer Idol
Legendary Artifact
Whenever Mindstealer Idol becomes transformed, gain control of target creature for as long as you control this permanent.
Sanctum of the Ancients 3GG
Enchantment - Dungeon
When Sanctum of the Ancients enters the battlefield, target player puts a 5/5 green Elemental creature token onto the battlefield. Then if that player is you or your teammate, sacrifice Sanctum of the Ancients.
Whenever you attack with creatures with total power 6 or more, transform Sanctum of the Ancients.
--
Relic of Might
Legendary Artifact
Creatures you control have +2/+2 and Trample.
Halls of War RR
Enchantment - Dungeon
When Halls of War enters the battlefield, target player puts two 1/1 red Goblin creature tokens onto the battlefield. Then if that player is you or your teammate, sacrifice Halls of War.
Whenever you attack with 3 or more creatures, transform Halls of War.
--
Head of the First Goblin King
Legendary Artifact
T: Target creature gets +3/+1 and gains haste until end of turn.
Crypt of Wails 2B
Enchantment - Dungeon
When Crypt of Wails enters the battlefield, target player puts a 1/3 black Scorpion creature token with Deathtouch onto the battlefield. Then if that player is you or your teammate, sacrifice Crypt of Wails.
Whenever you attack with a creature with Deathtouch or Lifelink, transform Crypt of Wails.
--
Psychephage Scepter
Legendary Artifact
B, T: Target opponent discards a card. Activate this ability only on your turn.
Maze of Silence 3WW
Enchantment - Dungeon
When Grove of Silence enters the battlefield, target player puts three 1/1 white Spirit creature tokens with Flying onto the battlefield. Then if that player is you or your teammate, sacrifice Maze of Silence.
Tap four untapped creatures you control: Transform Maze of Silence. Activate this ability only on your turn.
--
The Final Whisperstone
Legendary Artifact
When The Final Whisperstone becomes transformed, exile target card in a graveyard.
Each opponent can't cast a spell that shares its name with a card in exile.
Each creature an opponent controls can't attack or block if it shares its name with a card in exile.
if you remove the whole rigmarole of "target player puts a creature into play. if that player is you or a teammate, sac this card" and possibly remove a CMC from each card, it'd probably be a lot more elegant.
Legacy - Solidarity - mono U aggro - burn - Imperial Painter - Strawberry Shortcake - Bluuzards - bom
Improved version:
Waterfall Temple 3U
Enchantment (R)
When Waterfall Temple enters the battlefield, target player puts a 3/3 blue Drake creature token with flying onto the battlefield, then sacrifice Waterfall Temple unless that player is your opponent.
U: Gain control of target creature for as long as you control Waterfall Temple. Activate this ability as a sorcery, and only once.