Here's the deal. I'm a temporary PC who was tossed in by a DM who decided to let me play as a Priestess of Lolth (5e, 14th level, vs a party of 10th level PCs)

On my side, I have:

1. 2 Driders I can summon for ten minutes
2. The ability to turn myself into a Drider
3. Whip of Fangs, 4 heads (Poison, all that fun stuff)
4. 3 Drow followers, 2 assassins and a mage
5. The fact that I've installed myself as a friendly PC Sun Elf who spun a yarn about the orb I'm trying to steal from them being one of TWO, the "Eyes of the Yolchol," required to resurrect a follower of Lolth required to oversee a ceremony of world-ending proportions.

On THEIR side:

1. Half Orc Warrior who just got a sword of unknown magical properties
2. A blue Dragonborn, frost breath, flying and all
3. A Dwarven Paladin, party healer
4. A half orc/gnome spellcaster
5. A gnome Druid with a mouse familiar(?)
6. A gods-damned tiefling of unknown capability
7. The woodselven ranger I need to take the orb from.

Tactical Advantage:

1. I'm in their party as a cleric, and they think I work for Tatiana of the Summer Court.
2. They're in the Feywild, and I've already contracted a promise from them to "Help me find the Drow female leader and finish this, and you'll have the eye and favor of my Lady, whatever is in her power to give." Oh semantics and wordsmithery, how you've helped balm my possible (pretty much assumed-upon) death with beyond-the-grave-Lolth-screw-withery.
3. There's a cliffside nearby the site of the battle. The party ended looking upon a camp of elves (the drow servants disguised with Seeming by their Mage). The hammer should fall very quickly once the game begins.

I'd like to inflict MAX damage on this party before I croak, and I'm certain the DM wouldn't have placed a temporary PC in me like this unless that was to be my party-decimating goal.  

I've never played with everything behind me to murder a party of PCs, AS a PC, and I'd like to make this as fun as possible, for me.

How can I do maximum damage before I get to 0 hit points?