Icebox has a very small mid area of the map. This makes it a very A and B rush style map.
Viper is the best smoke Agent for Icebox due to her wall covering most lines of sight on offense and defense.
Killjoy and Sage are some of the best sentinels for Icebox. Killjoy's turret can control all of mid. Sage's walls are very strong to create cover for planting the spike.
Icebox is Jett's playground. You can create many elevated off angles and take aggressive early round fights on defense. On offense, you can create a lot of pressure with your smoke and dash.
Always be careful of a late lurk mid or Kitchen. Typically enemies will send one lurk through mid often since it's not as easy to do 3-2 splits.