Blackbird card
The blackbird card should be the most powerful card in the deck, no other card should be able to capture it
The Official Rules play with the Blackbird as the highest card and no others can capture it. The Western Wyoming rules play with the Blackbird as the lowest card.
If neither of those rule sets work for you, you should take a look at creating your own rule set. To do this, go to Settings, Active Rule Set, Manage, then +. Among other things, you can decide which cards to include and whether or not the Blackbird is the highest trump card.
Let me know if you have questions. Thanks for playing!