Spider potion effects, and exp gain from them

Spider potion effects are seriously insignificant to actually fighting them. Basically, spiders are not enough of a challenge. Please make it so potion effects on spiders can stack and so they can get various levels of potion effects, similar to the rarity of mobs spawning with gear, and enchanted gear. On that note, make sure to increase the exp gained from spiders with potion effects similarly to how that works with armor on mobs.