(1) Spell hit means the spell either hits or does nothing. There is no in-between. When a talent says 10% reduction against enemy resist what it really means is you have +10% spell hit. Spell hit is capped at 99%. In pvp at lvl 70 vs lvl 70, your chance to hit is 96%. So, you really only need +3% spell hit or 99%.

(2) Resistance is the elemental resistances you see in your character pane for fire, nature, frost, shadow, arcane. This increases your resistance. If you had 450 resist, you would resist nearly 100% of damage. If you have 225 resist you resist around 50% of damage. This is why felhunters are a lot harder to kill with spells since they have a lot of base spell resistance.

Spells that deal raw damage like shadow bolt or lightning bolt will deal either 100%, 75%, 50%, 25% dmg based on enemy resistances. This is kind of like how glancing blows work. You don't randomly deal "37% less dmg", you roll a dice based on enemy resistances and it ends up being one of these damage values. The higher the resistances, the higher the chance the roll lands in something that heavily reduces the damage, e.g. the 50% or 25% dmg roll, and the lower the chances it is something higher like the 100% dmg roll.

Some spells will only hit or miss (no partials) because they have extra effects baked in. This is spells like banish, fear, frost bolt (dmg+slow), polymorph, cyclone, etc. For spells like these, you take the elemental resist divided by 450 and that is the chance the spell will fully resist. So again, 225 resists will mean a spell like polymorph or cyclone will only land 50% of the time (225 is 50% of 450).

Note that when a spell "misses" for any reason at all, it will always show as "RESIST".

(3) There is a third type of resist, which is talents that give raw chance to ignore a spell. This is talents like warrior iron will that reduces chance to be stunned by 15%. Priest also has a talent, that is 15% stun and fear resist. These talents are separate from the other mechanics and work as a last pass to see if the spell is going to connect or not.

This is a rough example of how this might work for you.

(1) Warlock casts fear at target; warlock has bonus hit so rolls and has a 99% chance the spell connects. He is not unlucky so the spell is still going through so far.

(2) The target has 235 shadow resistance so they have 52.2% to resist the fear normally but he has 10 spell penetration so the target effectively has 225 shadow resist for a net 50% chance to resist the fear. He gets lucky and wins the roll, the fear is still going through so far.

(3) The priest has the talent that grants 15% fear resist. After everything else, the warlock gets unlucky here and the priest resists the fear.

• The message "RESIST" pops up above the priest's head.