You gain the following benefits.
Jolt to Life
When you cast Spare the Dying, you can modify the spell so that it sends a jolt of electricity through the target, reviving it. The target regains a number of Hit Points equal to your Artificer level, and each creature of your choice in a 10-foot Emanation originating from the target makes a Dexterity saving throw against your spell save DC, taking 2d4 Lightning damage on a failed save or half as much damage on a successful one.
You can modify the spell this way a number of times equal to your Intelligence modifier, and you regain all expended uses when you finish a Long Rest. The Lightning damage of this feature increases by 1d4 when you reach Artificer levels 11 (3d4) and 17 (4d4).
Reanimator's Tools
You gain proficiency with Alchemist's Supplies. If you already have this proficiency, you gain proficiency with one other type of Artisan's Tools of your choice.