Hi! I'm planning my next campaign (starts in march) and I've had an idea for an encounter that many World of Warcraft players have seen before - The "Fight against very big immobile creature" and was wondering how I should go about setting up the combat map/token/etc.
#Unique Enconter Planning
half sentinel
summer elbow
If the surrounding terrain isn't really important, then a monster=map works fine.
If the surrounding terrain matters, then a transparent PNG of the monster scaled as needed is superimposed over the existing terrain map (as its own layer)
hushed pendant
If it's gargantuan the sky is literally the limit on how big the token might be. So if the token is immobile, you're going to want to make movement necessary for the players or else they will just sit there and wail away. First, I'd add terrain features. Full cover for the players, elevation for ranged attacks, means of getting there (ramps, stairs, ladders, portals, etc.)
Then I'd start thinking about area effects, lair actions preferably, so the players need to keep moving. Legendary actions can help here, too.
Then I'd think about making it a staged fight, maybe at half hp it changes, burrows, whatever. Something happens and the players need to change their strategy completely. Maybe minions appear. Or the earth erupts. You get the idea.
Make everything thematic to your big bad.
Hope that helps!