Cheapest priced copy (Forgotten Realms Commander): $0.69 at Card Kingdom, near mint, their price list as of .
Immovable Rod 
Artifact · Rare · Forgotten Realms Commander · #7
You may choose not to untap this artifact during your untap step.
Whenever this artifact becomes untapped, venture into the dungeon.
{3}{W}, {T}: For as long as this artifact remains tapped, another target permanent loses all abilities and can't attack or block.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.69 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 7 | Rare | $0.69 | — |
| Forgotten Realms Commander | 276 | Rare | $0.99 | — |
13 rulings from Wizards of the Coast
- 23 July 2021If you somehow venture into the dungeon while a room's ability is on the stack, you will continue on in the dungeon. If you're already in the last room, complete that dungeon and start a new one.
- 23 July 2021Moving into a dungeon room will cause its room ability to trigger.
- 23 July 2021If you target an Aura with Immovable Rod's last ability, it will lose its enchant ability and be put into its owner's graveyard because it can't legally enchant anything. An Equipment that loses its abilities loses its equip ability, so you won't be able to move it that way, but it will stay attached to the creature it's equipping, if any.
- 23 July 2021Choosing the dungeon or room to venture into is part of resolving the venture into the dungeon keyword action. Once that choice is made, players may not respond until after the appropriate room ability has triggered.
- 23 July 2021To venture into the dungeon, a player moves their venture marker into the next room of the dungeon they are currently in. If they aren't currently in a dungeon, that player instead chooses a dungeon card from outside the game, puts it into the command zone, and moves their venture marker onto the first room.
- 23 July 2021Some abilities still work even if they have been removed. Specifically, static abilities that change an object's types or change an object's colors will still apply even if those abilities are lost.
- 23 July 2021A player may only have one dungeon in the command zone at a time.
- 23 July 2021Dungeon cards are not part of a player's deck or sideboard. In both constructed and limited formats, players can use any dungeon card when they venture into the dungeon.
- 23 July 2021Once you resolve the last room ability of a dungeon, that dungeon is now completed and is removed from the game.
- 23 July 2021If a creature has a characteristic-defining ability that sets its power and/or toughness loses that ability, the power and/or toughness (as appropriate) become 0.
- 23 July 2021The player venturing into the dungeon chooses which dungeon they will venture into. They may choose a dungeon that they have already completed this game.
- 23 July 2021You can only move forward (well, downward) in a dungeon, never backwards or sideways.
- 23 July 2021Dungeons are removed from the game as a state-based action.