Skullbriar, the Walking Grave shares counters

[Korath]

Describe the Bug:
If there's more than one Skullbriar, the Walking Grave owned by a given player (even if one or more are tokens, or other cards copying a Skullbriar), they share their counters.

Which card behaved improperly?
Skullbriar, the Walking Grave.

Which update are you using? (date, name)Which type? (duel, gauntlet, sealed deck)
Dev master from about three weeks ago, 8865b7c.

What exactly should be the correct behavior/interaction?
Each Skullbriar, the Walking Grave represented by a card in a public zone keeps track of the counters on that specific card. Skullbriar tokens keep their counters when they die or are exiled (or are somehow anted or put into the command zone), but the counters cease to exist when the tokens do, the next time state-based effects are checked. Other cards copying Skullbriar keep their counters, but the counters cease to exist the next time they change zones (ruling).

Are any other cards possibly affected by this bug?
Some repros:

1. 1. Put a Skullbriar, the Walking Grave on the bf and another in your hand.
   2. Add a counter onto the one on the bf, say by attacking or with Dragon Blood.
   3. Kill (or exile) it, say with Murder.
   4. Cast the one in your hand.
   Expected: There's a Skullbriar in your graveyard with a counter, and one on the bf under your control without a counter.
   Actual: There's a Skullbriar in your graveyard without a counter, and one on the bf under your control with a counter.
2. 1. Put a Skullbriar, the Walking Grave on the bf under your control, another on the bf under the AI's, and a Clone in your hand.
   2. Add a counter to the Skullbriar you control on the bf.
   3. Kill it.
   4. Cast your Clone, and select the AI's Skullbriar to copy.
   Expected: There's a Skullbriar in your graveyard (or exile) with a counter, one on the bf under the AI's control without a counter, and a Clone on the bf under your control without a counter copying Skullbriar.
   Actual: There's a Skullbriar in your graveyard (or exile) without a counter, one on the bf under the AI's control without a counter, and a Clone on the bf under your control with a counter copying Skullbriar.
3. 1. Put a Skullbriar, the Walking Grave on the bf under your control, another on the bf under the AI's, and a Spitting Image in your hand.
   2. Add a counter to the Skullbriar you control on the bf.
   3. Kill it.
   4. Cast your Spitting Image targeting the AI's Skullbriar.
   Expected: There's a Skullbriar in your graveyard with a counter, one on the bf under the AI's control without a counter, and a Skullbriar token on the bf under your control without a counter.
   Actual: There's a Skullbriar in your graveyard without a counter, one on the bf under the AI's control without a counter, and a Skullbriar token on the bf under your control with a counter.
4. 1. Put a Skullbriar, the Walking Grave on the bf under the AI's control, another in your hand, and a Spitting Image in your hand.
   2. Make a token copying the AI's Skullbriar.
   3. Add a counter to your Skullbriar token.
   4. Kill your token.
   5. Cast the Skullbriar in your hand.
   Expected: Each player controls a Skullbriar with no counters.
   Actual: Your Skullbriar has the counters the token had (and the AI's has none).

Also, though I didn't bother to test it - Cards that care about the power or toughness of a card in a graveyard or exile (or ante, or the command zone, or the stack (possible when casting directly from the graveyard or exile)) don't see any power/toughness-modifying counters.

[Aswan jaguar]

I confirm all bugs and the last about:

Cards that care about the power or toughness of a card in a graveyard or exile (or ante, or the command zone, or the stack (possible when casting directly from the graveyard or exile)) don't see any power/toughness-modifying counters.

[Korath]

Another significant repro:

1. Put a Skullbriar, the Walking Grave on the bf under your control.
2. Add a counter to it.
3. Kill it.
4. Return it from the graveyard to your hand with Raise Dead.
5. Cast it.

Expected: Your Skullbriar has no counters.
Actual: It has counters, despite having been moved through a non-public zone.