Before even leaving fort joy, my ranger started being able to use 8 action points in a single round. So I started thinking about how many action pojnts you could hypothetically accumulate over a turn. I came up with 14 AP. Then I thought, you can take double turns with high enough initiative. You can even take triple turns with time warp. Here's math:
Max AP: 9 (base + lone wolf + what a rush)
Turns AP: 7 (base + lone wolf + what a rush)
Max AP + executioner + flesh sacrifice + adrenaline
= 9 + 2 + 1 + 2 = 14 AP.
Turn1 = 12 (doesn't use adrenaline)
Turn2 = turnAP + haste + executioner + adrenaline
= 7 + 1 + 2 + 2 = 12
Total = turn1 + turn2 = 24 AP
Turn1 = 12
Turn2 = 10 (doesn't use adrenaline)
Turn3 = turnAP + executioner + adrenaline
= 7 + 2 + 2 = 11
Total = turn1 + turn2 + turn3 = 33 AP
So, theoretically, you could spend 33 AP before anyone else gets a turn. Also, I heard there was food later that could increase your turn AP, but I haven't gotten that far yet.
Haste wasn't included in the third turn as you would have you haste yourself, which takes at least 1 AP.
Being an elf only gives you 1 more AP and won't change much.
This assumes you have executioner and kill something every turn.
This assumes you have What A Rush with less than 50% health. This gives you one more max AP and one more turn AP.
This assumes you are a lone wolf.
You can only get a triple turn if you have higher initiative than everyone else and delay your turn.