This upgrade will reduce the damage received from the enemies but also slow our units
There's 3 tier of upgrades
Tier 1
Cost: 200 gold, 100 crystals
Duration: 30s
Reduce damage received by 10%
Slow down ally units speed by 13%
Tier 2
Cost: 400 gold, 200 crystals
Duration: 60s
Reduce damage received by 15%
Slow down ally units speed by 18%
Tier 3
Cost: 600 gold, 300 crystals
Duration: 120s
Reduce damage received by 22%
Slow down ally units speed by 26%
