The following condition means before turn 6, opponent's has at least 2 pirate minions were killed.
opp_graveyard(count(), played_turn<6,pirate=true) > 2
The following condition means opponent has played 2 same cards, it may don't have 'Reno Jackson'.
opp_player(count(),played_duplicate=true) > 0
"spellcard" and "spell" are almost no difference, you can use it as alias.
my_hero - it's your hero card in the center board.
my_player - it's the controller, holds all the global board data like mana, turn etc.
my_self - it's the card itself defined in .json file.
If there are minions A,B and C on board, if you want to set minion C attack first ( the search tree node to be expanded first ), you can set card C's OnBoardPlayPriority value higher.
Remember 'Priority' value can not affect board's final value, it only controls the best move search tree expanding priority, so affected branch can be searched earlier or later.