(Answered) Line of sight, submerged units and physical attacks

[c_gee]

Over on reddit, a user asked a question about whether or not he could perform a DFA on a prone mech that was hiding in a depth 1 water hex, which got me scratching my head. I'm pretty sure that if the attack were allowed, it would be extremely risky, however, I'm not certain the attack declaration would be allowed.

It's been suggested that physical attacks do not require LOS to be declared (Paul ruled so here), but as far as I can tell, TW page 99 clearly states that LOS is a requirement for declaring attacks (though there are a few exceptions) and the rule doesn't differentiate between weapon attacks and physical attacks.

TW page 99 also says:

Adjacent Ground Units: Units in adjacent hexes always have
LOS to each other, unless one unit is completely underwater
and a unit in an adjacent hex is not.

With that in mind, TW also says this on page 109:

Depth 1 Water: ’Mechs in Depth
1 water receive partial cover (see
Partial Cover, p. 102).
A ’Mech standing in Depth 1 water
may make underwater attacks with
leg-mounted weapons, as well as
attacks from weapons mounted in
any other location against units not
underwater, provided the target
unit meets the normal requirements
for each type of attack.

Which suggest that a CRD-3R with SRTs in the legs (for example) standing in depth 1 water could fire his leg-mounted SRTs at something in his front arc that was fully submerged, even though he doesn't technically have LOS to something that would be fully submerged.

Further, page 144 says:

Depth 1 Water: A ’Mech standing in Depth 1 water may
make any physical attack, provided the unit meets the normal
requirements for each type of attack. However, the physical
attack cannot be made against a unit that is underwater, unless
the attack begins underwater as well. For example, a ’Mech
standing in Depth 1 water adjacent to a submerged submarine
in Depth 1 water can only make a kick attack, since the kick attack
occurs completely underwater. The ´Mech cannot make any other
attack, including a charge or death from above attack, against the
adjacent submarine because a portion of the attack would take
place outside the water.

I've read through the current TW errata and there doesn't seem to have been any changes to these excerpts.




So... My questions (in no particular order) are:

1) How could the mech in the above quoted text make that kick attack against a submarine if it can't see the submarine?

2) How can the CRD in my example above fire SRTs at a fully submerged target in its front arc if there's no LOS?

3) Other than when using artillery and LRM indirect fire, are these cases where LOS isn't actually required to make the attack declaration?

4) Would an attacking mech be allowed to declare a DFA or charge on a target mech that moved out of LOS behind a building, hill or woods? What if a friendly unit had LOS to the target? Would the attacker then be allowed to make that charge or DFA?

5) Is LOS a requirement for making physical attacks?

6) Could OP's mech actually make that DFA against a prone mech that was in depth 1 water?

[c_gee]

Looking into things some more WRT my scenario posed in question #4, I came up with more related questions that I feel aren't clearly answered in TW.

Consider the following scenario:

1 - Attacker A (70 ton Grasshopper) has won initiative and is on one side of a row of level 2 buildings (CF of 54) and Target B is 2 hexes away on the other side of the buildings.

2 - During the movement phase, B chooses to not move.

3 - A decides he wants to DFA B. Here's where things become unclear, because TW doesn't appear to indicate exactly when during A's move the DFA declaration is made.

Does A's player declare the DFA and then pick up the mini and move it to the adjacent hex to B (the building hex), OR does he move the mini first and then declare the DFA?

Order of operations seems to matter here.

If all attack declarations require LOS, it would seem to follow that A has to move the mini first and then declare the DFA (which also seems to clutter up how things work with double-blind play as outlined in TO, but that's another matter), otherwise, A couldn't declare the DFA (or a charge for that matter), which would also be true if LOS was being blocked by a hill/trees/water/smoke and not just by a building.

If, on the other hand, the mini is being moved first, then LOS would be obtained as soon as A moved the mini to the top of the building hex adjacent to B... Which seems reasonable but then raises a slew of other issues that raise questions not clarified in TW. Such as:

If A has to jump to the top of the building before he can then declare a DFA on B, what if the building can't support his weight? I don't think this is what the spirit of DFA intends, but things aren't entirely clear. Let's skip this for a moment and move on.

Once A has made his declaration and all movement for the turn ends, where is A actually located during the Weapon Attack Phase? Is A standing on top of the level 2 building? The building would collapse. What if the building had a CF of 72? The building wouldn't collapse but could it be shot out from under A during the weapons phase?

I'm certain all BT players (myself included) assume that A is in mid air and not standing on the building, but what if we changed the scenario so that the building was 4 levels high (and A still only has 4 jump MP)?

TW's rules for DFAs indicate that A actually jumps into B's hex but is placed in the adjacent hex. What if B had a friendly unit B2 who was already on the building? Clearly two mechs can't occupy the same hex, so where is A and can B2 shoot at him?

Page 149 of TW indicates that A is considered to be adjacent to B and 1 level higher than B or 1 level higher than the hex A occupies (the building), whichever is higher. So if the building is a level 4 building, A is considered to be 1 level above the building (putting him in the air 5 levels up), despite the fact that he only has 5 jumping MP. If B2 is on the building does that mean that A is going to collide with B2, or is A now 1 level higher than B2 (which puts A at level 7 - quite the jump for the Grasshopper)?

I'm certain that I'm not alone in accepting the intent of the rules and that A temporarily is located 5 (or 7 if B2 is on the building) levels up, despite not actually being able to jump that high for the purpose of making DFA rules work, though I'm just pointing out that TW isn't terribly clear on some of the details.



If you really want a head-scratcher, consider the same scenarios in double-blind play.

If LOS is required to make a DFA and A attempts to jump into an "empty" hex behind a building but there happens to be an enemy mech B there, does A land on the building instead (and possibly collapse it) or does A automatically DFA B? What if B is a tank? A can share the hex with B so does A just land in B's hex or does A land on the building or does A DFA B? Again, what if B2 is on the building?




I suppose the simplest solution to all thes DFA/charging issues is to say that LOS isn't a requirement for physical attacks and write an errata to that effect, though I wonder what other issues might surface from an official errata like that.

[Xotl]

Okay, long question, long delay.  Sorry.

1) How could the mech in the above quoted text make that kick attack against a submarine if it can't see the submarine?

A: Per the Underwater LOS Table on p. 109, a mech in depth 1 water has LOS to underwater targets.

2) How can the CRD in my example above fire SRTs at a fully submerged target in its front arc if there's no LOS?

A: Same reason as #1: it has LOS in this case as well.

3) Other than when using artillery and LRM indirect fire, are these cases where LOS isn't actually required to make the attack declaration?

A: No.

4) Would an attacking mech be allowed to declare a DFA or charge on a target mech that moved out of LOS behind a building, hill or woods? What if a friendly unit had LOS to the target? Would the attacker then be allowed to make that charge or DFA?

A: DFAs and charges are not declared until the attacker is in the hex in front of the target (see errata, or the BMM).  As such, you should always have LOS to the target, unless the target is completely submerged; a DFA or charge against a fully submerged target is illegal in any case (per p. 144).

5) Is LOS a requirement for making physical attacks?

A: Probably.  However, I can't think of a time where this is really relevant, after taking into account the rulings and errata mentioned above.

6) Could OP's mech actually make that DFA against a prone mech that was in depth 1 water?

A: No, per p. 144.


Most of your follow-up questions are addressed by the errata, which eliminates the ambiguity on DFA and charge declarations.  The issue of stacking and death from aboves is discussed on TW p. 149.  The BMM also clarifies the height of the attacker when DFAing and how it interacts with the number of jump jets available (though the beta is a bit vague and things are being clarified even further for the final; this is being backported to TW via upcoming errata).

Anything remaining that is unclear?