If a different copy of Carnival Barker enters the battlefield, or if Carnival Barker leaves the battlefield and returns, it's a new object and its ability can be activated
Some are applicable in all forms of play, while others are restricted to specific types of games
So searching "Dark Charizard 4/82" into a search engine will reveal that the card is from the Team Rocket TCG expansion released in 2000
Darksteel Forge Artifact Artifacts you control have indestructible
Sacrifice and Regenerate You cant regenerate a creature to save it from being sacrificed because regenerate can only prevent a creature from being destroyed, not from being put into the graveyard via another way, Suppose my opponent casts [c]Diabolic Edict[/c], which forces me to sacrifice a creature
Absorb Absorb is doing what control decks love most, which is a hard counter and some lifegain to tank early damage