Bottomless Vault

Oracle Text

Bottomless Vault enters the battlefield tapped.

You may choose not to untap Bottomless Vault during your untap step.

At the beginning of your upkeep, if Bottomless Vault is tapped, put a storage counter on it.

T, Remove any number of storage counters from Bottomless Vault: Add B for each storage counter removed this way.

Card Rulings

10/4/2004 It is only considered “tapped for mana” if you activate its mana ability and generate mana from it.
10/4/2004 This enters the battlefield tapped even if a continuous effect immediately changes it to something else.
10/4/2004 If the land is tapped by some external effect, no counters are removed from it.
10/4/2004 Counters are not lost if the land is changed to another land type. They wait around for the land to change back.
10/4/2004 Whether or not it is tapped is checked at the beginning of upkeep. If it is not tapped, the ability does not trigger. It also checks during resolution and you only get a counter if it is still tapped then.