1 Fatigue = 1 Movement Point
1 Movement Point = Drink 1 Potion
Therefore 1 Fatigue = Drink 1 Potion, right?
So here's the funny stuff: My Road to Legend campaign is at 482 Total Conquest and Grey Ker is dominating the game via a monstrous combination of advances.
He's got 12 health, 9 Fatigue, a Ranged trait of 3 Black and 1 Silver and has the following skills: Rapid Fire, Born to the Bow, Marksman and Eagle Eyes. He's equipped with the Elven Robe, the Ring of Protection, the Ghost Armor rune, the Archer's Charm and the Scythe of Reaping. Oh, and he also gains a further +1 Armor from the Crown of the Elder Gods worn by another hero.
So his attacks are like this: 1 Blue, 2 Green, 3 Black and 1 Silver, gaining Sorcery 2, Range + 5, Pierce 3, +1 Range or Damage per Surge, whole attack counts as aimed.
What all this boils down to is that if Grey Ker goes for 2 Attacks in a turn, his sequence of attacks looks like this: Make first regular attack, spend 2 Fatigue for first additional attack, spend 2 Fatigue for second additional attack, spend 2 Fatigue for third additional attack, spend 2 Fatigue for fourth additional attack, spend last Fatigue to drink a Fatigue Potion, make second regular attack, spend 2 Fatigue for fifth additional attack, spend 2 Fatigue for sixth additional attack, spend 2 Fatigue for seventh additional attack, spend 2 Fatigue for eighth additional attack.
That's 10 attacks of the kind mentioned above in a single turn! And since another hero has the Leader skill (the one where he can place orders on other heroes), he can even have a Rest order on top of that, making him capable of firing machine gun salvos for as long as he has Fatigue potions...
There isn't much that can take that kind of punishment.