Megalania are good to attack down from close ceilings, arthros to destroy armor, gas grenades again for bottlenecks and pop shooters, trip wires, um lol lots of things
Right before the attack starts spam the whole entrance with bear traps and spike walls. They’ll think you’re just panicking and they won’t expect how annoying that actually is to get past.
Also make a bunch of flare guns with the firework skins on them to shoot at the attackers to annoy them lol
Wyvs on turrets mode behind a turrets wall behind a clustered blockade of as much metal crap as you can put down, spike walls, signposts etc. If you can keep the blockade just outside the cave and the wall on the very edge on the entrance even better.