Upgrading spawners is quite expensive. So in addition to giving the player more experiene, maybe the spawners should also be buffed by e.g.
-Increasing the spawn rate
-Giving more drops
-Unlocking special forms of the mob.
Also, Tough mobs seem a bit useless. Maybe they should drop more loot as well.
-Increasing the spawn rate
-Giving more drops
-Unlocking special forms of the mob.
Also, Tough mobs seem a bit useless. Maybe they should drop more loot as well.