Rules for combining mecha are...weird.
Also, very vaguely worded.
For example, it doesn't say what kind of actions the augmenter can take, and how some interactions work; this is mainly due to these specifics not being asked about, I suppose.
Anyway, some clarity on the following matters, please:
0)Assuming Mecha #1(Base) and Mecha #2(Augmenter) combine...*This requires a standard action from the Augmenter(#2).
*Presumably, the Mechas need to be in some sort of minimum distance from each other(not covered in the rules).
*The Base Mecha(#1) gains X(Number of #2's HD)+Y(#2's Constitution SCORE) Hitpoints, which are not temporary hitpoints, increase his maximum hitpoints for the duration of the combination, and go away if the combination ends(much like bonus HP from temporary constitution increases).
*The Base Mecha(#1) gains Increased Size as Bonus feat for the duration of the Combination.
*The Base Mecha(#1) gains various, slot-dependant benefits based on the Augmenter's(#2) role(s); this requires him to have the relevant magic item slot free and available.
*The augmenter(#2) gains effective total concealment, as it cannot be attacked as primary target during the combination.
*The Base Mecha(#1) takes full damage from all attacks, and additionally, the augmenter mecha(#2) takes half the damage the Base Mecha(#1) suffers. This leads to the combined mecha effectively having a Vulnerability(+50% damage) to EVERYTHING. Increased HP and two different HP pools mitigate this(somewhat).
*If either mecha is destroyed, the combination ends immediately.
Now, the problems:1)ActionsUnder the "Cannons" role entry, it says...
The base mech may take a standard action to allow the augmenter to use a spell, spell-like ability or supernatural ability with a casting time of 1 standard action, or a full-round action to... you get the picture.
-snip-
This implies that the augmenter CANNOT normally cast spells, use (Su) or (Sp) abilities when combined. This is a severe limitation.
Furthermore, under the "Arms" role entry, it says...
The augmenter may attack in place of the base mech's attacks. It adds the base mech's Strength modifier as a bonus to its Strength score (or vice versa, if the base mech's Strength is higher), and deals damage as a creature of the combined mech's size.
This implies that the augmenter CANNOT attack independently from the base mech when combined. Even if he does, his attacks REPLACE the base mech's attacks, effectively halving the number of attacks they would have independently. This is a severe limitation.
So, my questions would be:
A) What kind of actions can an augmenter take while combined? My character concept will use the augmenter to boost himself/the party via Inspire Courage(possibly Dragonfire Inspiration). This requires Concentration to maintain -would such an action be possible? What about a -hypothetical- augmenter swordsage with the "Shadow jaunt" maneuver. Could he initiate it, and would it teleport the entire, combined mecha? What about Boosts and Counters?
B) What kind of actions can the *pilots* of the mecha take, apart from piloting their mechas?
The Champion class involves a literal transformation, thus circumventing this matter. The Mecha Pilot, however, is a seperate entity from his Mecha. While I assume he will not be able to act on his own(manifest powers, cast spells, etc) while controlling a Mecha, what about the situation when two mechas combine?
Are both pilots required to steer the Combined mecha, or can one pilot it and the other one perform other actions(such as manifesting Psionic repair damage to repair the Combined Mecha)?
2)Bonuses and Limitations of Combining MechaUnder 0), I have attempted to give a short overview of the current mechanics of combining mecha.
This subitem shall deal with this topic in detail, while evaluating wether or not the benefits outweigh the drawbacks, or if it is worth combining at all.
Bonuses gained from Combining Mecha:*Increased HP for Base Mech
*Total Concealment for Augmenter Mech
*Increased Size Bonus feat for Base Mech
*(Wings)Base Mech is treated as mounted; this allows for serious damage upgrades via Spirited charge, valorous weapons and the like
*(Legs)Base Mech may gain additional movement modes and/or increased movement speed; bonus to AC if augmenter has higher Dex
*(Arms)Augmenter Mech can attack instead of the Base Mech, benefits from increased size and strength
*(Cannons)Base Mech may transfer action to Augmenter Mech for spellcasting/manifesting/Sp/Su abilities; benefits from increased relevant ability score(s)
*(Armour)Base Mech takes 75% damage instead of 100%. The augmenter takes 75% damage instead of 50%, however, this 75% is based of the damage the Base mech takes.
[spoiler=Math]
Base Mecha = A
Augmenter Mecha = B
Both Mecha have combined, and take damage.
Normal:
Base Mecha takes X Damage. Augmenter takes X*0.5 Damage.
A = X, B = X*0.5
(Armour) augment combination:
Base Mecha takes X*0.75 Damage. Augmenter takes (X*0.75)*0.75 Damage.
A = X*0.75, B = X*0.5625[/spoiler]
This leads to an insignificant increase(+6.25%) of the damage the Augmenter Mecha takes, but to a significant decrease(-25%) of the damage the base Mecha suffers.
*(Head)Base Mech gains senses of Augmenter, gains bonus on Intimidate/Listen/Spot/Search based on Augmenter's ranks in these skills.
Penalties/Drawbacks/Limitations gained from Combining Mecha:*Augmenter cannot cast spells/manifest/use Sp or Su abilities normally
*Augmenter cannot attack normally
*Augmenter takes damage when the combined mech is damaged; this leads to an effective Vulnerability against everything. Split HP pools mitigate this drawback somewhat
*Base mech loses access to (a) magic item slot(s)
Summary of the above, and my opinion on the matterIMO, some augments are great(Armour, Wings), some are so-so(Legs, Head <-only if the augmenter has some seriously awesome senses akin to Mindsight that the base mech lacks!) and some are really, really bad(Arms, Cannons).
The problem of actions has been addressed already, and is in need of further clarification.
I also think that the bonus HP formula gained from combining mecha is a bit clunky, perhaps simply adding the Augmenter's HP as bonus HP to the Base Mecha could work.
Yes, I am aware that this would be *a lot* more powerful than the current mechanic, but due to the damage-taking mechanics of combined mecha, I am of the opinion that such an upgrade wouldn't be overpowered.
Of course, this is just that -my (probably not significant) opinion.