Nocturn + Mouthpiece + Conditioning

Juggernaut1981 wrote: Venenation requires a successful block before being played. So the 'before this action is blocked/before blocks are successful' window is long-closed.

The play sequence (for the Nocturn Sequence):

Vamp X has declared a block attempt to block Nocturn
Now other action modifiers can be played (such as stealth cards)
The Nocturn would now be blocked once the acting Methuselah passes on impulse and the blocking Methuselah does so as well.
Then the block is successful and the minion taps for blocking.
Then combat begins.

So in the space before you started the block attempt and the block being declared successful by both Methuselahs, there is space to play Mouthpiece, etc. If somehow the Nocturn cannot continue the action or dies, the action ends unsuccessfully, the block fails (since there is nothing to block) and the blocking minion untaps.

To be a bit more precise, the block is only declared successful by the acting player, when her predator passes on using the impulse during an action where the attempt to block has equal or more intercept than the acting minion's stealth.

Blocking minion definitely doesn't untap if Nocturn dies. He does not tap, which is clearly different (Wake with Evening's Freshness, ...) See Change of Target's cardtext.

Regarding the Tapping vs Entering combat, the Complete Rules Reference seems to show there are two different steps (IV. D 3 b, IV D 3 c) (also notice: action is unsuccessful). But that doesn't mean that you can squeeze something inbetween.
For example, it's been asked: Can I successfully block, tap, play Forced Awakening + Obedience? (in order to cycle a Forced Awakening)
Answer is no. (linked to that thread: groups.google.com/group/rec.games.trading-cards.jyhad/browse_frm/thread/807c408323f5e55a/60076d826f9eca3e )

@ Mael: You cannot play action modifiers when an action is blocked. You similarly cannot play action modifiers after action has resolved. Of course, rule 1.4 takes precedence.

Juggernaut1981 wrote: If somehow the Nocturn cannot continue the action or dies, the action ends unsuccessfully, the block fails (since there is nothing to block) and the blocking minion untaps.

Slightly off tagnet, could this method be used to ged rid off No Secrets from Magaji? Bleed with nocturn, Magaji attempts to block, Nocturn dies before combat --> burn No Secrets?

Whisker wrote:

Juggernaut1981 wrote: If somehow the Nocturn cannot continue the action or dies, the action ends unsuccessfully, the block fails (since there is nothing to block) and the blocking minion untaps.

Slightly off tagnet, could this method be used to ged rid off No Secrets from Magaji? Bleed with nocturn, Magaji attempts to block, Nocturn dies before combat --> burn No Secrets?

maybe. except No Secrets card text only mentions vampires.

Well, I would want a ruling from LSJ on the No Secrets thing.

I'm not sure if the block attempt would 'fail' in the sense of "If a minion fails to block" or if the block attempt is also cancelled since the action is cancelled because it cannot be continued...

There are no fail block.

Juggernaut1981 wrote: Well, I would want a ruling from LSJ on the No Secrets thing.

Define "thing".
Do you want a clarification on why No Secrets doesn't burn when the Magaji attempts to block a Nocturn who plays Conditioning?
That's because of cardtext.

Juggernaut1981 wrote: I'm not sure if the block attempt would 'fail' in the sense of "If a minion fails to block" or if the block attempt is also cancelled since the action is cancelled because it cannot be continued...

No Secrets from the magaji doesn't require the block attempt to fail in order to burn.
It only requires the block attempt to be unsuccessful (and the acting minion to be a vampire).

Which part is unclear?