It makes no sense the base damage to be reduced BEFORE any other multipliers are applied. Or, in this case, I suspect the multipliers are still applied to the full base damage, regardless of the fact it’s being reduced by 90%.
So if you have a 1000 dmg attack, it is reduced by 90% = 100 dmg. But then a damage increase is added based on the base damage, so 1000 dmg x 50% = 500 dmg. In the end, even if you distracted the creature, you still get hit by more than half of its damage - which is inconsistent with the distraction description (it says “Target damage is reduced 90% 1 turn” not “target base damage”).
What should happen is either the damage value reduced by 90% after all other damage multipliers are calculated (90 % of (1000 + 50% of 1000)) = 150 dmg
damage multipliers are applied to the reduced value (the distracted dmg) - 90% of 1000 = 100, then 50% increase for that 100 = 150 dmg again.
Whatever else is happening it is simply inconsistent. Why would you want a skill to reduce the damage of a creature by 90%, but still allow the creature to be hit by an untouched damage multiplier? Obviously, it’s even worse if the reduction is 50% and not 90%…
Also, it’s worth mentioning damage increase skills IGNORE armor too, when they shouldn’t. Probably based on the same flawed logic.