On the subject of minions, gas spores are a delightful addition to beholder lairs and fights. Have a nice, gusty lair full of tunnels that can have a popped gas spore blow those spores right onto the party if they are unwise about attacking when the wind is behind the spore, and they must ask themselves if that is a charging beholder or a gas spore blowing down the hall.

Reduce visibility and introduce wind walls to limit projectile range, and while the reduced visibility hinders the beholder, it also means the party has to get into explosion range to attack. The beholder can use stealth and angles of attack for hit and run tactics in the tunnels.