The only way to get through the Golden Grove is to beat the Gladiataur. The boss has a few more tricks than the rat king making it a bit more difficult. Use this guide to defeat him on your first try
Gladiataur Boss Guide
One his special attacks is Savage Swipe. He just puts his sword over his head and chops down at you for additional damage. This can be blocked but it doesn’t hurt that bad if you just want to fight through it.
His strong move is Everblade. This move should be defend against. He spins in a circle like Link would and does some serious damage if you don’t defend. If you get lucky when you defend he might drop a gold orb.
Once you bring him to a quarter of hp he will start to move like he’s going to charge you. Defend this attack and Droopy will toss his shield at his head.
Heal if you need to and switch minions when they get low on stamina.
Ni No Kuni Gladiataur Boss Guide
Start of with Mitey since he should have the most defense off all your minions at the moment. Just keep attacking him while he attacks you. Once he uses the move Everblade be sure to block. When he first used it on me I got a gold orb and was able to use Mitey’s super on him. You might want to switch to Oliver or Lehmal since they can do more damage.
After that expect him to use a Savage swipe or two. Block them if you have Mitey out but in all honesty it doesn’t hurt that much if you want to just take the hit.
At half hp he will throw his shield and sword off and start to glow red. At this point all he was doing to me was punching me over and over. Just fight through it and get him to half hp. If you get low use your heal.
At a quarter of his hp he will start to move his hoofs like he is about to charge. When you gain control switch to a minion that can defend and do so. After he goes through you Drippy launches a shield at his head to knock him over. Use Oliver when he is dazed to get a gold orb to drop out of him. I did a few auto attacks and when it started to drop I switched to Lehmal. Keep attacking him while he is dazed then when he recovers grab the gold orb for your super move.
This should be enough to finish him off. Nice job.