So a White Scars Assault Marine under the effects of "Swift Assault" (First Founding page 32) wields a "Power Lance" (First Founding page 99). Swift Assault says that I can get a free half action per turn as long as one of my actions has the sub-type "Movement" (excluding Dodge). The Power Lance says I can hit people 2m away and don't count as engaged in melee unless my opponent can hit me back.
Is he able to use the "Charge" Full action and not engage himself in melee?
If he can "Charge" and not engage himself, can he then use the "Move" action to get double his Agility in meters with jump pack (or 10m space marine bike) away from said enemy?
I haven't come across anything in my perusing of books that actually states it's melee range... Does this mean I can pull the above trick on something really big like a Mawlock because you have to be "adjacent" to an enemy to be "engaged in melee"?
Yes, the character can make a Charge action and still gain an additional half action as a result of Swift Assault.
The description of the power lance does not give you any special abilities you would not have with any other melee weapon with 'reach'.
Firstly, you MUST engage a target to attack him in melee (Core p. 244), even with a power lance, but this does not mean the other guy must be capable of engaging you. Certain large creatures (bio titans, mawlocs, and defilers for instance) are sufficiently large enough it can be assumed they can engage targets without allowing those targets to engage them (common sense rule).
Second, you DO NOT have to be attacked or hit by anything to be engaged. To engage a target in melee all you have to do is move close enough to be capable of attacking the target, and then simply choose to engage him.
Thirdly, when engaged (either engaging another, or being engaged) a character can ONLY use melee subtype actions.
- Therefore a character with a lance can engage a target with the lance but be too far away to be engaged by the target. The target can Dodge the lance attack but since he is not engaging the attacker, may not use Counter Attack.
- The attacker remains engaged with the target as long as he chooses to be engaged (since the target isn't engaging him).
- If the target chooses to move away from the attacker without disengaging he would suffer a free strike, as long as the attacker continues to choose to engage the target.
- If the attacker moves away from the target without disengaging nothing happens as the target is not engaging the attacker which means it cannot make a free strike against him.
- As long as the attacker chooses to continue engaging the target, neither can use any attack action that does not have the melee subtype.
- And, of course, the target can move towards the attacker and thus engage him with no penalty or free strikes.
As for your question, yes, your charge then half move example is perfectly legal. Though I would rule a Mawloc (being a big arse bug as it is) would have the 'reach' to engage you even with a power lance (that things arms are like 12 feet long at least, I mean come on). I'd let you get away with it against carnies and tyrants though.
Final thought: Jump packs only double your nomal move. A half-move is normally equal to your agility bonus in meters, but space marines in power armor are hulking, and hulking characters gain a +1 to their agility bonus for movement purposes.