diff --git a/hwe/sammo/API/Auction/OpenUniqueAuction.php b/hwe/sammo/API/Auction/OpenUniqueAuction.php
new file mode 100644
index 00000000..21c6e2ee
--- /dev/null
+++ b/hwe/sammo/API/Auction/OpenUniqueAuction.php
@@ -0,0 +1,71 @@
+<?php
+
+namespace sammo\API\Auction;
+
+use sammo\Session;
+use DateTimeInterface;
+use sammo\Betting;
+use sammo\DB;
+use sammo\DTO\BettingItem;
+use sammo\Validator;
+use sammo\GameConst;
+use sammo\KVStorage;
+use sammo\UserLogger;
+use sammo\Util;
+
+class OpenUniqueAuction extends \sammo\BaseAPI
+{
+  public function validateArgs(): ?string
+  {
+    $availableItems = [];
+    foreach (GameConst::$allItems as $items) {
+      foreach ($items as $itemKey => $amount) {
+        if ($amount == 0) {
+          continue;
+        }
+        $availableItems[$itemKey] = $amount;
+      }
+    }
+
+    $v = new Validator($this->args);
+    $v->rule('required', [
+      'itemID',
+      'amount'
+    ])
+      ->rule('int', 'amount')
+      ->rule('min', 'amount', GameConst::$inheritItemUniqueMinPoint)
+      ->rule('keyExists', 'item', $availableItems);
+
+
+    if (!$v->validate()) {
+      return $v->errorStr();
+    }
+    return null;
+  }
+
+  public function getRequiredSessionMode(): int
+  {
+    return static::REQ_GAME_LOGIN;
+  }
+
+  public function launch(Session $session, ?DateTimeInterface $modifiedSince, ?string $reqEtag)
+  {
+    /** @var int */
+    $bettingID = $this->args['bettingID'];
+    /** @var int[] */
+    $bettingType = $this->args['bettingType'];
+    /** @var int */
+    $amount = $this->args['amount'];
+
+    $bettingHelper = new Betting($bettingID);
+    try {
+      $bettingHelper->bet($session->generalID, $session->userID, $bettingType, $amount);
+    } catch (\Throwable $e) {
+      return $e->getMessage();
+    }
+
+    return [
+      'result' => true
+    ];
+  }
+}
diff --git a/hwe/sammo/Auction.php b/hwe/sammo/Auction.php
index a5282512..e4c127c9 100644
--- a/hwe/sammo/Auction.php
+++ b/hwe/sammo/Auction.php
@@ -3,7 +3,13 @@
 namespace sammo;
 
 use Ds\Map;
+use sammo\DTO\AuctionBidItem;
+use sammo\DTO\AuctionBidItemData;
 use sammo\DTO\AuctionInfo;
+use sammo\Enums\InheritanceKey;
+use sammo\Enums\RankColumn;
+use sammo\Enums\ResourceType;
+use sammo\VO\InheritancePointType;
 
 class Auction
 {
@@ -25,22 +31,213 @@ class Auction
   }
 
 
-  static public function openAuction(AuctionInfo $info)
+  static public function openAuction(AuctionInfo $info, General $general): ?string
   {
     $db = DB::db();
     $auctionID = $info->id;
     $auctionStor = KVStorage::getStorage($db, 'auction');
+
+    $openedAuction = $general->getAuxVar('openedAuction') ?? [];
+    $prevAuctionID = $openedAuction[$info->reqResource->value] ?? null;
+    if ($prevAuctionID !== null) {
+      //XXX: 이 구조보다는 차라리 DB에 insert로 넣는 게 나을 수도.
+      $prevAuction = new Auction($prevAuctionID, $general);
+      if (!$prevAuction->info->finished) {
+        return '아직 경매가 끝나지 않았습니다.';
+      }
+    }
+
     $auctionStor->setValue("id_{$auctionID}", $info->toArray());
   }
 
-  public function __construct(private readonly int $auctionID)
+  public function __construct(private readonly int $auctionID, private General $general)
   {
     $db = DB::db();
     $auctionStor = KVStorage::getStorage($db, 'auction');
-    $rawBettingInfo = $auctionStor->getValue("id_{$auctionID}");
-    if ($rawBettingInfo === null) {
+    $rawAuctionInfo = $auctionStor->getValue("id_{$auctionID}");
+    if ($rawAuctionInfo === null) {
       throw new \RuntimeException("해당 경매가 없습니다: {$auctionID}");
     }
-    $this->info = AuctionInfo::fromArray($rawBettingInfo);
+    $this->info = AuctionInfo::fromArray($rawAuctionInfo);
+  }
+
+  public function closeAuction(): void
+  {
+    $db = DB::db();
+    $auctionStor = KVStorage::getStorage($db, 'auction');
+
+    $this->info->finished = true;
+
+    $openedAuction = $this->general->getAuxVar('openedAuction') ?? [];
+    if (key_exists($this->info->reqResource->value, $openedAuction)) {
+      unset($openedAuction[$this->info->reqResource->value]);
+      $this->general->setAuxVar('openedAuction', $openedAuction);
+    }
+    $auctionID = $this->info->id;
+    $auctionStor->setValue("id_{$auctionID}", $this->info->toArray());
+  }
+
+  private function bidInheritPoint(int $amount, ?int $priority, string $now): void
+  {
+    $db = DB::db();
+
+    $auctionInfo = $this->info;
+    $general = $this->general;
+
+    $rawHighestBid = $db->queryFirstRow(
+      'SELECT * FROM ng_auction WHERE auction_id = %i ORDER BY `amount` DESC LIMIT 1',
+      $auctionInfo->id
+    );
+    if (!$rawHighestBid) {
+      throw new \RuntimeException('최고 입찰가가 없습니다.');
+    }
+    $highestBid = AuctionBidItem::fromArray($rawHighestBid);
+    if ($amount <= $highestBid->amount) {
+      throw new \RuntimeException('현재입찰가보다 높게 입찰해야 합니다.');
+    }
+
+    $rawMyPrevBid = $db->queryFirstRow(
+      'SELECT * FROM ng_auction WHERE general_id = %i AND auction_id = %i ORDER BY `amount` DESC LIMIT 1',
+      $general->getID(),
+      $auctionInfo->id
+    );
+    if ($rawMyPrevBid === null) {
+      $myPrevBid = null;
+    } else {
+      $myPrevBid = AuctionBidItem::fromArray($rawMyPrevBid);
+    }
+
+    $morePoint = $amount - ($myPrevBid ? $myPrevBid->amount : 0);
+    $currPoint = $general->getInheritancePoint(InheritanceKey::previous);
+    if($currPoint === null || $currPoint < $morePoint){
+      throw new \RuntimeException('유산포인트가 부족합니다.');
+    }
+
+    //여기서부터 입찰 성공
+
+    $newBid = new AuctionBidItem(
+      null,
+      $auctionInfo->id,
+      $general->getVar('owner'),
+      $general->getID(),
+      $amount,
+      $now,
+      new AuctionBidItemData(
+        $general->getVar('owner_name'),
+        $general->getName(),
+        $priority
+      )
+    );
+    $db->insert('ng_auction', $newBid->toArray());
+
+    $general->increaseInheritancePoint(InheritanceKey::previous, -$morePoint);
+    $general->increaseRankVar(RankColumn::inherit_point_spent_dynamic, $morePoint);
+
+    if ($myPrevBid === null || $myPrevBid->id !== $highestBid->id) {
+      $oldBidder = General::createGeneralObjFromDB($highestBid->general_id);
+      $oldBidder->increaseInheritancePoint(InheritanceKey::previous, $highestBid->amount);
+      //TODO: 전역 알림이 나타나야한다.
+      $oldBidder->getLogger()->pushGeneralActionLog(
+        "유산포인트 {$auctionInfo->id}번 경매에 상회입찰이 되었습니다.",
+      );
+      $oldBidder->applyDB($db);
+    }
+    $general->applyDB($db);
+  }
+
+  public function bid(int $amount, ?int $priority): void
+  {
+    $auctionInfo = $this->info;
+    $general = $this->general;
+
+    if ($auctionInfo->finished) {
+      throw new \RuntimeException('경매가 이미 끝났습니다.');
+    }
+
+    $now = TimeUtil::now();
+
+    if ($auctionInfo->closeDate < $now) {
+      throw new \RuntimeException('경매가 이미 끝났습니다.');
+    }
+    if ($auctionInfo->closeDate > $now) {
+      throw new \RuntimeException('경매가 아직 시작되지 않았습니다.');
+    }
+
+    if ($auctionInfo->buyImmediatelyAmount !== null && $auctionInfo->buyImmediatelyAmount < $amount) {
+      throw new \RuntimeException('즉시판매가보다 높을 수 없습니다.');
+    }
+
+    if ($auctionInfo->reqResource === ResourceType::inheritancePoint) {
+      $this->bidInheritPoint($amount, $priority, $now);
+      return;
+    }
+
+    //reqResource는 말 그대로 '구매자가 내야하는 자원'이다.
+
+    $db = DB::db();
+
+    $rawHighestBid = $db->queryFirstRow(
+      'SELECT * FROM ng_auction WHERE auction_id = %i ORDER BY `amount` DESC LIMIT 1',
+      $auctionInfo->id
+    );
+    if (!$rawHighestBid) {
+      throw new \RuntimeException('최고 입찰가가 없습니다.');
+    }
+    $highestBid = AuctionBidItem::fromArray($rawHighestBid);
+    if ($amount <= $highestBid->amount) {
+      throw new \RuntimeException('현재입찰가보다 높게 입찰해야 합니다.');
+    }
+
+    $rawMyPrevBid = $db->queryFirstRow(
+      'SELECT * FROM ng_auction WHERE general_id = %i AND auction_id = %i ORDER BY `amount` DESC LIMIT 1',
+      $general->getID(),
+      $auctionInfo->id
+    );
+    if ($rawMyPrevBid === null) {
+      $myPrevBid = null;
+    } else {
+      $myPrevBid = AuctionBidItem::fromArray($rawMyPrevBid);
+    }
+
+    $morePoint = $amount - ($myPrevBid ? $myPrevBid->amount : 0);
+    $resType = $auctionInfo->reqResource;
+    $minReqRes = match ($resType) {
+      ResourceType::gold => GameConst::$defaultGold,
+      ResourceType::rice => GameConst::$defaultRice,
+    };
+
+    if ($general->getVar($resType->value) < $morePoint + $minReqRes) {
+      throw new \RuntimeException($resType->getName() . '이 부족합니다.');
+    }
+
+    //여기서부터 입찰 성공
+
+    $newBid = new AuctionBidItem(
+      null,
+      $auctionInfo->id,
+      $general->getVar('owner'),
+      $general->getID(),
+      $amount,
+      $now,
+      new AuctionBidItemData(
+        $general->getVar('owner_name'),
+        $general->getName(),
+        $priority
+      )
+    );
+    $db->insert('ng_auction', $newBid->toArray());
+
+    $general->setVar($resType->value, $general->getVar($resType->value) - $morePoint);
+
+    if ($myPrevBid === null || $myPrevBid->id !== $highestBid->id) {
+      $oldBidder = General::createGeneralObjFromDB($highestBid->general_id);
+      $oldBidder->increaseVar($resType->value, $highestBid->amount);
+      //TODO: 전역 알림이 나타나야한다.
+      $oldBidder->getLogger()->pushGeneralActionLog(
+        "{$resType->getName()} {$auctionInfo->id}번 경매에 상회입찰이 되었습니다.",
+      );
+      $oldBidder->applyDB($db);
+    }
+    $general->applyDB($db);
   }
 }
diff --git a/hwe/sammo/DTO/AuctionBidItem.php b/hwe/sammo/DTO/AuctionBidItem.php
index 296a2df7..d16beffc 100644
--- a/hwe/sammo/DTO/AuctionBidItem.php
+++ b/hwe/sammo/DTO/AuctionBidItem.php
@@ -3,12 +3,14 @@
 namespace sammo\DTO;
 
 use sammo\DTO\Attr\JsonString;
+use sammo\DTO\Attr\NullIsUndefined;
 use sammo\DTO\Attr\RawName;
 
 class AuctionBidItem extends DTO
 {
   public function __construct(
-    public int $id,
+    #[NullIsUndefined]
+    public ?int $id,
     #[RawName('auction_id')]
     public int $auctionID,
     public ?int $owner,
diff --git a/hwe/sammo/DTO/AuctionBidItemData.php b/hwe/sammo/DTO/AuctionBidItemData.php
index 86f7e9d3..76d51e9d 100644
--- a/hwe/sammo/DTO/AuctionBidItemData.php
+++ b/hwe/sammo/DTO/AuctionBidItemData.php
@@ -2,11 +2,16 @@
 
 namespace sammo\DTO;
 
+use sammo\DTO\Attr\NullIsUndefined;
+
 class AuctionBidItemData extends DTO
 {
   public function __construct(
-    public string $ownerName,
+    #[NullIsUndefined]
+    public ?string $ownerName,
     public string $generalName,
+    #[NullIsUndefined]
+    public ?int $priority,
   ) {
   }
 }
diff --git a/hwe/sammo/DTO/AuctionInfo.php b/hwe/sammo/DTO/AuctionInfo.php
index d1b86113..7534081c 100644
--- a/hwe/sammo/DTO/AuctionInfo.php
+++ b/hwe/sammo/DTO/AuctionInfo.php
@@ -13,6 +13,8 @@ class AuctionInfo extends DTO
 		public string $type,
 		public bool $finished,
 		public ResourceType $reqResource,
+		public int $minAmount,
+		public ?int $buyImmediatelyAmount,
 		public string $openDate,
 		public string $closeDate,
 	) {
diff --git a/hwe/sammo/Enums/ResourceType.php b/hwe/sammo/Enums/ResourceType.php
index d24481d0..ca0f0348 100644
--- a/hwe/sammo/Enums/ResourceType.php
+++ b/hwe/sammo/Enums/ResourceType.php
@@ -6,4 +6,13 @@ enum ResourceType: string
   case gold = 'gold';
   case rice = 'rice';
   case inheritancePoint = 'inheritancePoint';
+
+  public function getName(): string
+  {
+    return match($this){
+      ResourceType::gold => '금',
+      ResourceType::rice => '쌀',
+      ResourceType::inheritancePoint => '유산 포인트',
+    };
+  }
 }