With the Add-On Pack you get access to 28 cards: 24 additional creature cards (12 new creatures with duplicates) and 4 additional Mindbugs (required to play the 4-player mode).
List of creature cards:- Bugserker (x2)
- Count Draculeech (x2)
- Creep from the deep (x2)
- Ferret Pacifier (x2)
- Froblin Instigator (x2)
- Goreagle Alpha (x2)
- Hamster Lion (x2)
- Hungry Hungry Hamster (x2)
- Hyenix (x2)
- Majestic Manticore (x2)
- The Lurker (x2)
- Turf the Surfer (x2)