Crashoban’s ability is somewhat similar to Crattle’s, but Crashoban’s is much more powerful. Normally, when you crash only a single gem (rather than a run of multiple same-color gems) you don’t get the height bonus at all. For example, suppose you have 12 gems in your gem pile and you’re trying to dig yourself out to survive. Imagine that your top three gems are all different colors, so getting rid of the top two will (unfortunately) require two different crash gems. Normally, crashing the first will send 1 gem to opponents, and crashing the second gem will send another 1 gem, for a total 2. But if you had Crashoban, you’d get a +4 height bonus for each of those, meaning you’d send 10 in total. It’s so strong that you can realistically win the game with Crashoban.
You can upgrade Crashoban to level 3, and his card shows that it costs 2 actions to do so. You can’t upgrade him to level 3 on the same turn that you got him to level 2, so you’ll have to wait a turn at least. Once you do upgrade Crashoban, just flip the card over. On the back, you’ll find purple’s level 3 creature, Crashizard: