I have just recently picked up the D&D 4th edition rulebooks and I’m a little confused about certain aspects of the rules regarding how to combine the rules regarding line of sight, cover, and area of effect.
Let's imagine the following situation:
Three PC ("W", "F" and "R") shook off the goblins that were chasing them. The Goblins are looking for them in the room North of where they took refuge. One of the goblins opens the door to where two of the player characters are hidding. The Wizard PC, who went ahead to explore the room to the right, overhears the goblin opening the door, encourages his mates to take cover and throws a Fireball spell in the middle of that room (C-9).
My understanding of the rules is that:
- The wizard in H-9 can legally cast Fireball through the doorway to C-9, whether he has "line of sight" to where it's going to land or not, as long as the square used as a point of origin for the spell is located less than 20 squares away from the caster.
- Being an “area burst 3” spell, the effects of the Fireball expand 3 squares from its point of origin to every direction (effectively creating a 7*7 square) .
In the example above, the spell’s area of effect is enough to fill the entire room and spill to F-9(not drawn on the map above, my mistake). As a consequence, 3 characters are located within the Fireball’s burst radius: - the goblin in C-6, against which the wizard ought to roll a dice against and who does not benefit from cover of any kind, but also, - the rogue and the Fighter who are literally caught in friendly fire: they aren’t entirely safe from spell’s effect but at least get some cover from the pillar in B-10. The action is resolved by the wizard having to roll against them but has to take the cover into account (-4 in that case).
- If the above is correct, would the situation be different for either of the PCs if she were in A-11, for instance? Wouldn’t her location relative to the pillar in B-11 “shield” her from the effects of the burst? She would then be safe, in addition to being “covered”?
- Am I correct in assuming that if the wizard was standing in F-9 instead and casting the Fireball in C-9, he would not get any cover from the open doorway between E-9 and F-9 and would risk being caught in his own spell?
- Am I correct in assuming that the wizard could legally throw a Fireball in C-9 if he were located in G-6, for instance (that would be 9 squares away)? My understanding is that area burst spells can pretty much be “hail Maries” as long as the caster is within range, yet I assume that wouldn’t work if the caster had no notion of what the room in the lower left corner looks like at all. Is that correct?
Thank you very much for your help.