Sacrifice of the Chain Master

When you cast Find Familiar, you can give summoned familiar a measure of extra vitality, in exchange for your own, and vice versa. You gain the following benefits:

• When the familiar is first summoned, its hit point maximum is permanently increased by 1, and it increases by 1 for every level you invest in warlock after you take this invocation.
• As an action, you can heal your familiar. Sacrifice any number of your own hit points; your familiar regains a number equal to half of these hit points (rounded up) as part of this feature.
• When an attack directed at you will bring you to 0 hit points, your familiar can instead use its reaction to take the damage. However, doing so results in its immediate death, and Find Familiar must be cast again for it to return.