Turf is used to unlock tier 4 towers and their skills. Each type of tower has three tier four upgrades. Each one has a specific cost, and each one has two skills.

Type Cost
Cheapest 20 Turf
Medium 30 Turf
Most expensive 40 Turf

All skills cost the same amount of Turf: 40.

Check the V-Search Center to see how much tower upgrades cost.