Targets of a Burning Arc Trap?

[Oli Ironbar]

The spell has a primary target, but also secondary targets of the caster's choosing within 15' of the first target.

In trap form, what are the different ways of deciding who gets hit in which order?

Burning Arc:

This spell causes an arc of flame to leap from your fingers, burning a number of enemies nearby. It deals 1d6 points of fire damage per caster level (maximum 10d6). For every additional target the discharge arcs to, reduce the number of damage dice by half (rounded down). Therefore, at 9th level, your burning arc deals 9d6 points of fire damage to the primary target, then 4d6 points of fire damage to a secondary target, then 2d6 points of fire damage to an additional target.

Each target can attempt a Reflex saving throw for half damage. The Reflex DC to halve the damage of the secondary bolts is 2 lower than the DC to halve the damage of the primary bolt. You may choose secondary targets as you like, but they must all be within 15 feet of the primary target, and no target can be struck more than once. You can choose to affect fewer secondary targets than the maximum.

[TxSam88]

1. GM Fiat (just choose)
2. closest to previous target
3. random roll

[Pizza Lord]

For this spell, when creating the trap, I would say the caster chooses the number of targets that will be affected (like casting the spell, since you can choose less). It will then affect the closest to the primary/triggering target. If they choose two targets, it arcs to one, if they choose three or more, it will arc to those (if they are within range, and no target hit more than once). The caster/creator basically chooses the max targets in most cases I would assume without some other reason.

[Mysterious Stranger]

Since the caster of the spell can choose the targets, I would say that the creator of the trap can choose the pattern for the secondary targets. That pattern can be anything the creator of the trap wants as long as it is legal for the spell. Since the creator does not know who the targets will be he has to have a preset pattern of targets. The pattern cannot rely on individual traits of the target like class, race, or equipment. They can however use things like position or distance.

For example, the secondary targets could be those at the maximum range, or nearest to the primary target. They could also do something like have it start with those on the left of the target going counter clockwise. Any simple clearly defined patter should work, but if there is any ambiguity it may result in the wrong target or fewer secondary targets being affected.