Question 1 -
The cards in question: Artifacts that do not specify "discard this to", but have limited uses.
Card examples: Covenant of Noah, Unsuccessful
The question: Are they discarded by game rule as soon as you use them, or at the end of the phase, or some other time?
Practical example: I play a battle winner on my evil character, my opponent says they're going to use Cov of Noah to negate my enhancement, can I chain Lying Unto God to negate his Covenant before it negates my battle winner?
Answered.
Question 2 -
Cards in question: Set-aside enhancements, heal enhancements, Territory-class enhancements, Dominants, etc.
Card examples: Pentecost, Torment, Angel of the Lord, etc.
The question: Do the above-mentioned cards actually physically enter play when you use them?
Practical example: Can my opponent use Cov of Noah to negate my evil set-aside, heal, or territory-class enhancement that I play during my preparation or discard phase?
Question 3 -
Is the Errata on Cov of Noah (see below) correct? If so, why does Unsuccessful not have a similar Errata?
Referenced Card Abilities -
Covenant of Noah (Pa)
Type: Covenant • Brigade: Blue • Ability: 2 / 5 • Class: None • Special Ability: Use as an enhancement or an Artifact. Interrupt and prevent one evil enhancement. Discard after use. • Errata: Use as an enhancement or an Artifact. You may discard this card to negate one evil enhancement.
Lying Unto God (G)
Type: Evil Enh. • Brigade: Multicolor • Ability: 2 / 3 • Class: none • Special Ability: Negate and discard an active artifact.
Unsuccessful (Pi)
Type: Curse • Brigade: Gray • Ability: 0 / 6 • Class: None • Special Ability: Negate the last good Enhancement played in battle (may be used once). • Play As: When holder chooses, negate the last good Enhancement played in battle (may be used once).