I think rewards should be based purely on an combination of raw HP damage, modified healing, and rezes. Those three items seem like they should be sufficient.
Reviving should not necessarily grant any reward. That would be profiting of other people's failure.
However, killing a target is important, since an enemy can still attack, even with 1% HP.
Nobody will stop shooting completely in order to steal a kill (because that is not how it works), but people might stop shooting a low hp target, because "the others will deal with it", in order to get more points from shooting something else.
Taking an enemy out of the fight is important and should be rewarded (at least a little bit).
healing [...] shouldn't be a linear reward. [...] you should get a bonus based on how close to death someone is.
The point of healing is not to have people almost die, but to keep them at full HP as good as possible, so that they can always engage in fights, without having to be scared to get sneezed on.
Your suggestion would promote risking the death of players, because healing low hp targets would grant a higher reward.
Not a good idea.
In Planetside2, as a Medic, it is more effective (for gaining points) to revive dead guys, than to heal them and prevent them from dying in the first place, so that is what medics do. The best thing that can happen is when people keep dying instantly after you revive them.
Something similar would happen with your suggested system.
This is not the point of being a healer.
Healers are supposed to be reliable supporters, not to only heal you, when they gain the most from it.
This rewards rescues, and doesn't reward heal spamming or overhealing.
Rewarding
rescues does not really seem necessary to me. The target has low HP, so there is much to heal, which means many points, anyway.
Overhealing would not be rewarded, because it does not restore any HP.
Heal spamming is exactly what a healer is supposed to do (good healers do it and try to keep everyone at full HP).
One thing I am not sure if it is possible is marking preventative damage.
Shield a player, all absorbed damage grants you points (low amount).
In case that is what you meant.
I am not sure exactly how to weight resurrections, possibly based on the ratio of enemy strength (lots of minions vs a few powerful mobs) to friendlies within a certain range.
As i already said: if reviving someone grants a reward, people are more likely to let them die.
[...] rewards should not be based on any sort of event but rather be a cumulative effect [...]
If the war is supposed to be happening in separate events, those
events should definitely have their own participation counter that starts and ends with the duration of the specific event.
If that is not the case, there would not be a way to measure and reward skill with any kind of participation rewards.
With your system, every raging potato would be able to accumulate points and get good rewards by simply playing forever.
[...]as long as you are in combat the points will accrue [...]
This would take away any way of rewarding skill through the point system.
This allows for players to play for longer periods of time and get larger rewards
It allows every noob to get any kind of reward, if they just play long enough.
It also rewards you for risking your health.
That is bad.
but it also allows players to come and go as they please without being penalized.
No. It does the exact opposite.
People will try their hardest to find a way to accumulate as many points as possible, so they will NOT go as they please (or they will go, but stay logged in and run a bot) to keep the points.
If rewards accumulate, logging off or going afk can kill off huge amounts of progress (when returning, you have to get back to that high reward level).
Playing only for a short time would be guaranteed to grant a shit reward, because not many points could be accumulated.
Uninterrupted playtime would be the single most important thing when it comes to good rewards and lead to people playing for unhealthy long times.
BUT
If rewards are given out right after every event, you can leave any time and never lose more than a few minutes of progress.
You can log in, be top player in one event, get a good reward, log off.
It also doesn't give any bonus to player idling.
Indirectly, it can, because players will find a way to not lose their points while being afk.
If they don't find a way, they are punished for going afk.
With my suggested system, an idle player does not gain anything, but does not lose anything either.
The more you directly participate, the more you get out of it. The more efficiently you participate, the more you get out of it.
Same for my suggested system. Except mine would reward skilled play, yours would reward marathon gaming sessions.
This is where skill and having the right tools for the right job comes into play.
Skill would be close to irrelevant with your suggested reward system.
Playtime would beat everything.