That tends to happen with Sami. Here's a tip!
For the first 50% of Sami's health, she will randomly fling a debuff that, if the afflicted member uses ANY skills (physical skills, healing, buffs), it summons one sprite per action. You can use potions.
To avoid this, have your party members pay very close attention to who has the debuff, so that you can minimize the amount of sprites summoned! Your positioning should be spread out. Have the tank pull Sami to the opening where the wood planks are (behind her), and you'll need to position the other four party members around the square room's corners.
Two healers is optimal, since if one is afflicted, the other can heal. Bard and cleric, or cleric and shaman.
You're looking at a square, with Sami in the top middle of this square.
-Have the healers stand at the top two corners.
-The other two DPS should be long-ranged. Have them stand at the bottom two corners.
Why should you do this? The AoE she casts is large, but not large enough to hit more than one party member if they stand in this arrangement!
If you pay attention to debuffs, it'll be fine! After Sami gets down below 50% health, she will ONLY cast this on the tank! Keep that in mind. ^_^
Save yourself from sprites today. >: