How do mines/charges and guardian interact? There are lots of weird scenarios you can get into with mines/charges and guardian. Here are a few questions:

1. When a mine/charge goes off, who chooses the order of the attacks?
2. When a mine/charge hits a unit with guardian that only has one model left and also hits a second unit; what happens if the guardian unit chooses to guardian the other unit and dies before the mine/charge damage roll happens? Is this even an option?
3. When a mine/charge hits a unit with guardian and another unit; what happens if the guardian unit chooses to guardian the other unit and the only model that was in range of the mine dies due to guardian before the mine/charge damage roll happens?
4. Same as #3 but LoS instead of range (the only model in LoS of the mine/charge in the guardian unit dies before the mine/charge roll).

Hmm, interesting scenarios. Certainly presents some highly-specific tactical opportunities.

1. With charge tokens, I think it's fairly clear that the owner of the charge chooses the order. With mines, it doesn't seem clear at all. I would play it as the player who did not trigger it chooses the order, but don't see rules to necessarily back that up.

2. If the guardian unit dies during the attack on the other unit, then the second attack (against the guardian) wouldn't occur since there is nothing left to attack. Yeah, it's certainly an option. And not a bad option I think, if you consider that the guardian unit may have been defeated anyway from its own attack...

3. Assuming the non-guardian unit is attacked first: when it comes time to perform the attack against the guardian unit, the unit is not in range of the weapon so you don't have any dice to attack with.

4. Similar to #3, since you don't have LOS to the unit (and LOS is one of the requirements) you don't perform the attack even if some minis in the unit are still in range.

Answering to 1:

With charges, we play it as the one detonating the charge performs the attack, in any order he want.

With mines, the card says that when the unit moves, roll the die to see if explode. We understand that the unit moving must roll the die. If mines goes booom, we treat as player whose unit detonates the mine performs the attack. It hurts more when you roll hits on yourself ?

1. I think the answers to the other questions might hinge on this one. Intuitively, I would think the player who controls the unit activating the mine should choose the order (because one player is always the attacker, the other the defender, and these units are being attacked), although there is no rule that accounts for this.

Quote

When using an area weapon, perform a separate attack against each unit that is in line of sight and at the range indicated by the number on the range icon.

When a charge or condition token detonates, either through an ability or some other game effect, perform a separate attack against each unit (regardless of which player owns that unit) that the token has line of sight to, using the area weapon, surge conversion chart, and weapon keywords

Reading that, assuming that both players are affected, perhaps one player executes all their attacks, then the other player follows? This should be cleared up.

2. Since each attack is separate, you can't choose to guardian an attack that hasn't happened yet. So, if I understand your question, there are two units, one with guardian. If the "first" attack kills the guardian unit, then they are not around when the "second" attack happens.

3 and 4. I have no idea. Due to the nature of the game we must treat each attack in a sequential manner. However, the attack (if using fluff) is really ~simultaneous. It seems to me that, since each attack is separate, some attacks that were valid would no longer be valid, depending on the order of defenders chosen. This works with the current rules.