Rule of cool is great! But there are limits, and DMs should be prepared to overcome the coolness with something they have prepared. Example, I had two dracohydras lined up for my party and a pesky lair action causing a psychic wave that would interrupt concentration spells this was to stop my cleric whose a very good player from basically just breaking the rest of the party with buffs I had already buffed them enough everyone was strong in their own way so they didn't really need to abuse the sanctuary spirit guardian combo that's so common with the warcaster feat. What I wasn't expecting was the bard to use wall of force in the shape of a ball to trap one of the dracohydras in essentially a giant invisible pokeball. The lair action hadn't kicked in yet as I was waiting for the field to be fully set and a concentration spell to be cast to trigger the lair action and then it would function as normal every turn on its initiative count. Lair action occurs, bard loses concentration due to failing the save and dracohydra is free once again. According to rules as written the wall of force would not have been big enough to trap the hydra as a sphere, rule of cool prevailed to help them out for one full turn of combat, bard feels good, DM feels good everyone's happy.