Help with Resist

[KLS]

It's base resist, you always get it, I only used the even level and 0 resist to illustrate.

Resist above 250 is far from useless there are mitigating factors. If the enemy is higher level than you, if they're using a spell that can partial, if they're using a spell with a -resist mod it all provides benefits.

If the value going into the calculation is 250 after all mitigating factors then you have 100% chance to roll a less than 100. Which means everything is either a partial or total resist.