At last you've been awakened from your slumber! Ever since those pesky paladins from the Order of the Sun foiled your plans of plunging the world into an Eternal Night, destroying your phylactery, you had to resort to gathering energy in the limbo like a common ghost and awaiting until the right conjunction for your remaining underlings to bring your back to life through an intrincate ritual involving the sacrifice of several virgins.
You hoped you'd be met by a grand army ready to be led for conquest, but you've been met by a small family in a basement. They sacrificed a bunch of babies, presumably their own. They start blabbing something, so you cast a small spell to understand their language.
"Great and powerful spirit, our harvests have been terrible, please aid us ending the famine that has been plaguing our region!", the peasants beg, holding one of your now ancient grimoires.
In anger, you intended to just zap those fools with a powerful magical blast, but no magic came out.
Ever since you achieve lichdom, you became very aware of the flows of magic and so you pause to feel the magic in the environment.
This region is very mana poor, so much so that it is draining your mana at an astounding pace - that small spell to understand their language drained so much mana from you you got spent!. You must find a mana source to nourish yourself fast, or back to limbo your go for another aeon of energy gathering.
Tasting the mana winds, you feel mana coming from the directions. None of those is exactly what you were looking for, but they might be enough to sustain you until you can find something better.

> Fire mana from the south, possibly from a volcano
> Water mana from the west, possibly from an island
> Nature mana from the south, possibly from a forest