To greatly speed up combat - if you specify the target (single or AOE) and you know the attack roll - you know the defence condition and whether it is a hit - could you automate the damage reduction all in one or two clicks. (select target/select weapon or spell. Basically player initiative choosing target. Instead initiative - roll to hit/damage see if this hit and then manually subtract damage. You would also need to take of conditions of target and attacker. For AOE you can specify multiple targets before attack. Maybe you couldn't not use it for every attack but basic melee would benefit.
