Manual fix instructions if your deck got hit by the Arena hacker:
1. Click on Modify Deck in the Arena.
2. When you're in the skill point screen, press the Tab key on your keyboard.
3. There should be a yellow highlighted box.
4. Use your arrow keys to move the highlighted box.
5. If your mark multiplier got hacked to be abnormally high, move the highlighted box to the "-Intellect" button and hold down Enter until it returns to the acceptable limits. If your mark multiplier is still as you set it before, skip this step.
6. If your HP got hacked to be abnormally high, move the highlighted box to the "-Stamina" button and hold down Enter until it returns to the acceptable limits. If your HP is still as you set it before, skip this step.
7. If your max number of upgrades got hacked to be abnormally high, move the highlighted box to the "-Wisdom" button and hold down Enter until it returns to the acceptable limits. If your upgrade limit is still as you set it before, skip this step.
8. If your draw multiplier got hacked to be abnormally high, move the highlighted box to the "-Dexterity" button and hold down Enter until it returns to the acceptable limits. If your draw multiplier is still as you set it before, skip this step.
9. Move the highlighted box to the necessary "+" buttons and hold down Enter to get any stats that were reduced (usually Wisdom) back to normal.
10. Your remaining number of skill points should now be as you set it before the hacking.
11. Rebuild your deck in the deckbuilding screen.