Remember that scene from Game of Thrones when Jon Snow and others were stuck on a rock in the middle of a frozen lake, assaulted by undead? Let's do the same at your game table!

There are four phases (five if we count the initial map without cracks) of this dynamic battlefield, with more holes appearing with each round. Consider the following ideas:

• Place something important on the rock, something that would require the entire party to get there.
• Use the holes as spawn points for opponents or safe areas for swimming creatures, like Water Elementals — they can disappear under ice and reappear from a different hole.
• Use the slippery surface to prevent players from escaping  to the safe edges of the lake. It can be treated as difficult terrain, or moving more than 20 feet in one round requires an ability check that results in the creature falling prone on failure.
• Ice-cold water is dangerous, requiring a saving throw and dealing cold damage to any creature that falls into it.
• If you want to be absolutely brutal, have some enemies attempt to drag player characters into the water.

You can find the base variant with or without grid, together with a scene image on my patreon for FREE. If you are interested in all phases of this dynamically changing map, consider subscribing!