Bubbles
Can contain thin air, or a creature.
1. Burst by Venom, if empty then the way is clear
2. Burst by Venom, if occupied then that creature is realesed
3. Burst by Fire
4. Burst by a Roller
5. Burst by Spike
6. Burst by Footballs
7. Bubble and occupant are destroyed by any explosion
8. Bubble and occupant are destroyed by a Crusher