The casket has limitless range and all enemy units in line of sight suffer the effects of looking into despair itself !
The casket is like an incantation and so is always cast successfully with a power level of 2D6 (ie an average of 7). The enemy can attempt to dispel as usual.
The problem with the casket is 3 fold:-
1) If the enemy expect you to bring one he or she we do the utmost to negate it's powers by bringing dispel scrolls or by fielding multiple spell casters.
2) needs to be kept out of combat otherwise you cannot use it. This reveals a 'hidden cost' to the casket. You will need to deploy a unit specifically to protect it. If the enemy has flyers you will need to take carrion to hold them up (remember your carrion cannot be routed but they are not great in combat so will be destroyed quickly unless you take them in numbers)
3) it's a rare unit so no screaming catapult if you are playing a 2000 pt game ! This is a big loss.
4) It is only effective against lower leadership units (8 or lower). An enemy with a leadership of 9 will only lose 1 wound per unit (no armour save) every other turn (on average) IF the casket 'spell' is not dispelled.
Despite these drawbacks remember that the casket is a great battlefield addition. Personally, I would only use it in larger 3000 pt battles against lowish leadership enemies like humans, skaven or gobbos.
Note: It is fantastic against enemy artillery crews. You should always have line of sight (if they're on hills) and their leadership is never great unless they are accompanied by a character.
