Magic: The Gathering included its own Blitzball mini-game in the form of the enchantment card Sidequest: Play Blitzball
Invasion tactics and Katara, The Fearless are good examples
[cards] Myr Enforcer Deadly Dispute Blood Fountain [/cards] Grixis Affinity, a deck many players hate to face, is notoriously difficult to outvalue once it establishes its board, primarily due to cards like Deadly Dispute and Blood Fountain
Considering that it also has some bite to it with the 130-damage Hydro Splash for a reasonable Energy cost, it's a great card to have if players can quickly evolve it from a Basic Load to the Stage 2 Ludicolo
Event rules and store policies vary, and you should always check with the organizer if youre unsure
To get them from your Attraction deck to the battlefield, you'll need to open them, using cards like "Lifetime" Pass Holder