Dumbledore in His Prime

Gavin stared at the topic on the blackboard, lost in thought.

For now, what limited his use of the Obscurus was the enormous amount of life force it consumed.

Gavin still did not know exactly what life force was, but he could already feel its presence.

Whenever he used the Obscurus, he felt something steadily being drained away.

That something had to be life force.

He currently had three ideas for overcoming this limitation.

He wrote them on the blackboard.

[First: tonics]

The kind Ernie drank every day seemed capable of replenishing life force.

The logic was simple—

The Obscurus consumed life force, and tonics replenished it. If the two could balance out, he could theoretically use that power without limit.

So he had asked Ernie for a few bottles to test.

The results were not encouraging.

First, he released a small amount of the Obscurus and gauged the loss of life force by feel. Then he drank a tonic to see whether it eased that drained sensation.

The experiment was extremely subjective and hardly scientific.

But Gavin had no tools or methods for measuring life force. All he could do was rely on observations that were as objective as he could make them.

After several tests, Gavin reached a conclusion—

The tonics did help, but they did not truly replenish life force.

The Obscurus consumed the body's own life force, while a tonic supplied a temporary reserve.

After he drank a tonic, the Obscurus consumed roughly 20% to 40% less of his own life force, drawing on the tonic's reserve instead.

But drinking more tonics did not help.

The amount drawn from his own body remained fixed.

With a tonic's help, the toll of using the Obscurus was cut by about half, but he still could not use it