This enemy has decent health and moderate attack damage, along with Area Attack. It also might slow the movement of your cats, so beware. It will be a threat the first time you meet it and an even bigger one the second as the second time you meet it, as it has an extremely high buff those times.
This enemy is much stronger than the normal Sir Seal you find in some other levels, but it has longer time between attacks and 2 knockbacks, unlike his red counterpart, and is half as fast. To kill it, spam meatshields while also spawning in strong hitters like Valkyrie and Bahamut Cat to take it out.
Later on, just use any attacker with more than 220 range and he will die quickly.