Craftland.org

On the game runescape there is a Wilderness and in this wilderness there is these ghosts called "Revenants". Revenants is ghosts of different type of levels and forms that travels across the mining world to hunt players down shooting magic and got a high level of regeneration and can freeze the player from moving every few second, here is more details on Revenants http://runescape.wikia.com/wiki/Revenants" onclick="window.open(this.href);return false;. Keep in mind Revenants will chase after the nearest player with the appropriate Time played even if he/she is on the other side of the map and Revenants Magic hits through armor! And armor protects against close ranged attacks. You could also introduce a magic resist enchantment to the Armor for protection against the Rev's Magic Damage.

List of different Reverants the Mining world could have:

Chicken Revenant Lvl 1: Ghost chicken that chases players with a total play time of 1 second to 3 hrs, Got 10 Health, Magic does 1 dmg, Its close ranged attack does 3 dmg. Uses Regeration 1, Applies slowness 1 to the player.

Pig Revernant Lvl 2: Ghost Pig that Chases players with a total play time of 3 hrs - 10 hrs, Got 20 health, Magic does 3 dmg, Close ranged attacks does 5 dmg. Uses Regeration 1, Applies slowness 1 to the player.

Sheep Reverant Lvl 3: Ghost Sheep that Chases players with a Total play time of 10 hrs - 24 hrs., Got 50 health, Magic does 5 Dmg, Close ranged attacks does 7 Dmg. Uses Regeration 1, Applies slowness 1 to the player.

Cow Reverant Lvl 4: Ghost Cow that Chases players with a Total play time of 24 hrs - 50 hrs, Got 70 Health, Magic does 7 Dmg, Close ranged attacks does 10 Dmg. Uses Regeration 1, Applies slowness 1 to the player.

Moa Reverant Lvl 5: Ghost Moa that Chases players with a Total play time of 50 hrs - 100 hrs, Got 110 Health, Magic does 9 Dmg, Close ranged attacks does 12 Dmg. Uses Regeration 2, Applies slowness 1 to the player.

Panda Reverant Lvl 6: Ghost Panda that Chases players with a Total Playtime of 100 Hrs - 250 hrs, Got 220 Health, Magic does 11 Dmg, Close Ranged attacks does 16 Dmg. Uses Regeration 2, Applies slowness 1 to the player.

Penguin Reverant Lvl 7: Ghost Penguin that Chases players with a Total Playtime of 250-500 Hrs, Got 350 Health, Magic does 15 Dmg, Close Ranged attacks does 19 Dmg. Uses Regeration 2,
Applies slowness 1 to the player.

Aer Bunny Reverant Lvl 8: Ghost Aer bunny that chases Players with a Total play time of 500- 1k Hrs, got 500 health, Magic does 20 Dmg, Close ranged attacks does 25. Uses Regeneration 2,
Applies slowness 2 to the player.

Iron Golem Reverant Lvl 9: Ghost Iron Golem that chases Players with a Total play time of 1000+ Hrs, Got 1500 Health, Magic does 30 Dmg Close ranged attacks does 35. Uses Regeneration 2,
Applies slowness 2 to the player.

Also you can only attack the Rev that got the required played time.

Those 30 Damage attacks would kill you instantly if it hits through armor. And adding a whole new enchantment to compensate that would only help with that seems a bit pointless. regardless, the idea itself is a pretty interesting one. I think it could be a neat addition if done right.

personally, I don't get why mining worlds are commonly made harder than a normal world is. IMO, a mining world is there to keep the lands in the normal, building world from being destroyed by players hunting resources. I feel like adding in 'bosses' of a sort might discourage players from going there in favor of easier resource-gathering in the overworlds. With attacks that pierce armor, the iron golem would kill any player in 2 hits, 1 hit if they don't have any extra hearts.

The panda revenant (the current revenant that would chase me)- can kill from a range in 2 hits, would take about 10 hits for me to kill. I don't think I can draw a bow 10 times in between those 2 attacks unless it attacks really slowly. Also, I'm assuming that these revenants would still spawn wherever they please like normal mobs do (like right behind you). That would be inevitable death, for me at least.

EDIT:
I suppose if they are added though, it would be interesting to see some unique mobs for the higher-level ghosts, perhaps similar to spectres from the gemcraft series.

for those who haven't played gemcraft:
[spoiler][/spoiler]
the idea being that it flies (ie. it can evade obstacles like trees or steep slopes) at the cost of being more visible.

The drops on revs are amazing ~.~