The Uca Crusher is not as outwardly dangerous as the other Large enemies, as it only does low to average damage. However its Tidal Slam has a higher than average critical chance and it will knock your front row heroes to the back of the line and stun them, effectively disabling melee focused units for several turns. Its true damage dealing attack is Arterial Pinch which does very low damage, but can cause a bleeding effect that will do 8 damage a round in Veteran levels and 10 in Champion levels. And with it's high HP pool and PROT stat, it will take some time before you can send it back into the dark abyss it sidled out of.
This enemy has no apprentice level.