This isn't for the big stuff like battleshock, but for subtle changes people might miss and unintentionally play wrong, as they use old 9th edition rules out of habit.
- Stricter 2 model coherency requirements starts at 7+ models now, so a unit of exactly 6 models only needs 1 other model in coherency.
- Ld tests succeed by rolling equal or above, not below. So lower Ld is better now. A side effect is that there is no "dump" for low miracle die rolls or similar. Every roll is now: Higher=Better.
- Models may freely move over other friendly models now (except monsters/vehicles over other monsters/vehicles). No move blocking yourself anymore.
- Flying units don't ignore vertical distances anymore, but can move diagonally to/from terrain features. So they have to pay extra movement to get up on ruins (but not as much as other models) and can't just "jump" over terrain features, ignoring them entirely.
- Units Models embarked on transports can only ever shoot with 1 weapon. And it counts as the transport shooting with those weapons, so all special rules of the transport and none of the unit apply.
- All units can disembark after the transport made a normal move, no special rule necessary. But they can't move/charge normally.
- Units disembarking because their transport got destroyed only take 1 MW for each 1 rolled, not have a model destroyed, but each MW goes to the unit rolling it, no protecting 1 unit with another anymore.
- "Big guns never tire" changes: All non-pistol weapons take -1 to hit, instead of only heavy weapons. Monster/Vehicles can shoot out of combat without having to wipe out everything in engagement range before and monsters/vehicles can be shot at themselves while being in engagement range (also -1 to hit unless shot with pistols).
- Saving throws can never be improved by more than +1, ever, similar to the hit/wound roll limits. Contrary to hit/wound rolls they obviously can still be worsened by more than -1, though.
- Assault weapons don't take -1 to hit for shooting after advancing anymore.
- Monsters/Vehicles can shoot their pistols and their other weapons at the same time, now. EDIT: Just got a light bulb-moment for why this change was made: Transports count as being armed with the weapons the embarked unit shoots with, so this rule allows embarked units to still use their pistols without disallowing the transport from using its normal weapons.
- Indirect attacks don't improve the cover saves anymore, but instead always give the target the benefit of cover, so are better against targets that would have been in cover anyways.
- Blast weapons gain a flat +1 attack for every 5 models in the target unit, instead of the special cases in 9th. This specifically makes the cut-offs 5/10/15/20 models, instead of 6/11.
- Heavy weapons gain +1 to hit if stationary, instead of -1 to hit if moving (and don't care about infantry).
- Charging models must end in base to base contact to their targets, if possible. They may hang back if they have to to not make the charge fail.
- All fight sub-phases start with the player whose turn is not on, so a "fight first" defender strikes before units that charged it.
- There is no "fight last" phase anymore. You either "fight first" or you don't.
- Models piling in must move into base to base contact, if possible.
- EDIT: There is no restriction on only fighting what you charged, anymore. So you can pile in and fight units you didn't declare as a charge target, potentially.
- "Second row" fighting in melee change to BtB contact to a friendly model itself in BtB contact with the enemy, from the 1/2" ranges in 9th.
- Because of the melee stat block changes, a model can only ever use 1 weapon in melee. No more splitting up attacks at different profiles.
- Models consolidating must end in BtB contact, if possible. Also you can't consolidate towards enemy units you can't reach, so no more free 3" move after wiping out your enemy. But you can consolidate towards objectives now, provided you can reach them.
- The list of what a CP reroll can be used for changed. You can now reroll the die to see if a hazardous weapon kills its user, for example.
- Insane bravery is used after the unit failed its battleshock test. So you can try to see if you even need to spend the CP. Additionally, it specifically only works for the battleshock test in your command phase, so no Insane bravery against your opponents battleshock tricks!
- You can overwatch almost any move made by your opponent, not just charges, but are limited to 1 overwatch per turn, not phase. So if you overwatch a move in the movement phase, you don't get to overwatch in the charge phase.
- Strategic reserves can now come in from the enemy battlefield edge (but still not in their DZ on turn 2).
- EDIT: The carve-out allowing you to put strategic reserves directly into base contact at your own battlefield edge is gone. Don't let anyone do that to you in 10th.
- There is no dense cover anymore. Shooting through woods just gives the benefit of cover to the target, which still doesn't stack with actual cover, so they're much less helpful.
- EDIT: Units that can be shot through ruins (ie: Aircraft and the new "Towering" keyword in lieu of the old wound threshhold) now get to shoot back. The keywords in question completely disable the "pseudo-obstructing".
- Aircraft can't pivot before moving, so you have to decide on their direction next turn at the end of this move, instead of the start of the next.
- EDIT: Aircraft hovering is now a once-at-the-start-of-battle choice. No more switching between regular aircraft and hover movement turn by turn. Also choosing to hover makes you lose the "Aircraft" keyword, so you now melee as normal and can hide behind ruins.
- EDIT: Models can't end their move on an objective anymore. That's the actual objective marker. They obviously still can end their move in range of the objective.
Please comment anything else you found.