Originally Posted by me
All spear and pike units get +8 attack against Cav, plus a further unspecified bonus from having the Spear Attribute.
they also get an unspecified defense bonus vs. charging Cav from their spear attribute and an unspecified penalty vs. infantry from the same source.
Based on the fact that (with fixed Shields or working pikes), many Cav seem to die on impact, I also suspect a reflected charge value.
The formed charge is NOT a push-back type effect at all. A Cav-man that impacts somebody will inflict an attack on them (how this is calculated is unclear). If they survive it and are directly in front of the Cav-man, (he can hit those to the side as he plows into a unit), the Cav man then sometimes drops dead so the man hit must always get a kind of free attack in. I'd guess spears/pike get to reflect charge too as they seem much more successful than their performance in general melee vs. Cav suggests they should be.based on the fact that Spears will also often kill an enemy charging Cav man even if he kills them I would also say it is probable that in addition to reflect charge giving a Cav bonus, it also gives the model with it a free attack back regardless of weather the Cav man kills him or not. I'm not 100% sure of how this works, but based on the functioning of various units I believe the free attack of the spearman and the attack of the formed Cav charge are resolved simultaneously for them, rather than the Cav man going first and the impacted infantryman, (if they are not a spearman/pikeman), getting a free attack back if the survive If the Cav man survives the free attack back, then he may be stopped or he may inflict another hit on the guy he has collided with and even get it reflected back again. This is probably where momentum comes in in M2TW, and probably also mass as it would be that that determines momentum. Naturally the attack and defense of both the charging Cav and defending soldier are considered in this, but high defense is far more important for receiving a charge than high attack. If your defense isn't above a particular value (varies with the type of attacking Cav), you haven't got a chance full stop of stopping them.
A note on pikes: The formed charge effects seem to mostly rely on the Cav man hitting or passing extremely close to their target. Normally coming into contact with a targets weapon will also cause the model holding it to take a formed charge hit.
However, this is not the case with pikes against Cav charges. In this case the Cav man does not inflict a hit on the pikeman, but the Pikeman does inflict a hit on the Cav man. It is also clear that even if the Cav man survives this hit, he will not inflict a hit on the pikes.
On the other hand a Cav man that hits or passes very close to the pikemans actually body will inflict a hit on him. So it's clearly related to either the Spear-Wall or Long Pike attributes. I'll need to do more tests to confirm which attribute is responsible though.
However it's clear that Cav that do a formed charge into braced pikes are unable to inflict any formed charge attacks on the pikemen despite being in contact with their weapons. However, it is equally clear that the pikes can hit the Cav, and with some kind of reflected attack, and that doing so, (if it doesn't kill the Cav), doesn't always stop him from continuing to count as charging.
Most likely, (based on observational evidence), their is a line of code in either the spear wall formation or the long pike attribute that reads something like, "can_suffer_attacks_from_formed_charges=false", and it is set to true for all other weapons, attributes, and circumstances. This would explain how the Cav can count as charging, whilst the pikemen still don't suffer any damage from it in a situation where for the effects of reflect charge they are in contact with the Cav.
Extra Reflect charge info: it's quite clear from the fact that only pikes attacked head on and spears hit head on actually get to reflect the charge, (and that spears and pikes that are moving and thus holding their spears/pikes up in the air), that the reflect charge ability is localized to only affect enemy that come into contact with the units actual weapon, and not just those that come into contact with the unit whilst it has that weapon out.
The defense bonus from spears appears to be quite large as fixed Spear militia with Gold Armour (base defense of about 14), are about as charge resistant as DFK (defense 21) so it looks like the bonus is about 50% extra to the defense score.