Runescape Defence - The Crystal Shield
Degrades: Every 250 hits you take that did damage. No hit that does 0 (blue splat) qualifies against your shield. Cost from elf Islwyn: 750k Recharge cost from elf Ilfeen:
1st Charge: 750000gp, 2nd Charge: 600000gp, 3rd Charge: 450000gp, 4th Charge: 300000gp, 5+ Charge: 150000gp(price does not change from the 5th charge on)
The Crystal Shield is arguably the best anti-range shield in RuneScape. It beats every shield in range at ALL decay states except the granite shield. Even then, thats at 2/10. For melee defense, it's not too great. Mages could consider this to balance their weakness to Rangers in the wild.
The Crystal Shield also lasts a long time in non PvP combat. Since many of the monsters that players train their melee skills on usually hit zero (and not count to decaying the shield), the shield helps this out even further.
The Wilderness is the most hostile of the Player VS Player types available because players can be attacked and if killed, will lose all but their most valuable items. Killing another player in this area is referred to as PKing (Player Killing).
As one gets deeper into the Wilderness they can fight with other players further and further away from their combat level which makes it more dangerous (or easier if they are atacking a weaker player). Some areas of the wilderness only allow 1-on-1 battles, whilst other areas allow multi combat and potentially huge team wars.
The level of the wilderness tells you what level players you can engage in combat above and below your own combat level. For example, If you are in level 50 wilderness, you can fight people 50 levels below or 50 levels above. A pure is a player who only trains in certain skills to keep their combat level low. This Allows them to engage in combat with less equpped players, however their lack of certain skills means that they will not win every engagement.