can anyone explain to me how points are scored in the war?
Each alliance is worth roughly 1500 points total. Those points are divided proportionally among all the teams based on the health of their heroes. For each individual team, 2/3 of the points are awarded as each hero is killed, and the remaining third is awarded as a bonus when the last hero is killed.
To be exact, points are scored according to dmg dealt, not by heroes killed. So if you would leave enemy heroes alive with 1 hp each, you still gain most of the points that are allocated to that (not the last kill bonus part of course)