Magical Resistance
From Basin Wiki
When an offensive spell is cast, the target has two seperate chances to resist the attack.
First, there is a roll based purely on the level difference between the caster and the target. If the target is significantly higher level, the spell will usually fail completely. If the target is significantly lower level, the spell will very rarely fail. This first roll is why spell casting players have such a hard time landing spells consistantly on all monsters a few levels higher. In PvP combat, it is much less of a factor. A level 10 Mage can very often land polymorph on a level 60 player.
Formula needed for the first roll.
Second, there is a roll based on the level of the caster and the resistance stat of the target. Notice that the level of the target is not a factor in this roll.
Average Resistance = (Target's Resistance / (Caster's Level * 5)) * .75
Average resistance may be no higher than 75%. Of course, what it takes to reach 75% average resistance depends on the spellcaster's level. Against a level 1 spellcaster, it would take a resistance stat of 5. Level 20 would take 100 resistance. Level 50 would take 250 resistance. Level 60 would take 300 resistance. Level 63 would take 315 resistance.
Why is it called "average resistance?" For spells that don't cause immediate damage, you'll either totally take the hit or totally avoid the hit. The average resistance is the chance you'll totally avoid the hit. Adding the word "average" is a little redundant in this case.
However, when spells do cause immediate damage, it's not just a full hit or full miss situation. Damage spells be resisted for 0%, 25%, 50%, 75%, or 100% of their regular damage. Your average resistance can still be anywhere betweeen 0% and 75%. If your average resistance is maxed out, then there's a really good chance of 75% of the spell's damage to be resisted. There's also a fairly good chance of 100% of the spell's damage being resisted. A slightly lower chance of 50% of its damage being resisted. Small chances of only 25% or even 0% of the damage being resisted. It's a weighted average. Visualize it as a bell curve around your average resistance.
Example: Average Resistance vs. Level 60 Spellcasters
| Resistance Stat | Average Resistance |
| 0 | 0% |
| 25 | 6.25% |
| 50 | 12.5% |
| 75 | 18.75% |
| 100 | 25% |
| 125 | 31.25% |
| 150 | 37.5% |
| 175 | 43.75% |
| 200 | 50% |
| 225 | 56.25% |
| 250 | 62.5% |
| 275 | 68.75% |
| 300 | 75% |
Also see Blizzard's Page on Resistances
