Geminae felt the powerful pulse of mana leaving David, but didn't react.
He came for help to contain a dangerous being. If the mortal thought he needed an army to do so, then he would let him summon said army.
The ground rumbled violently as David's shadow suddenly expanded in all directions, hands piercing out of the ground. The hands quickly turned to arms and then to upper bodies.
A mix of skeletons, zombies, ghouls, as well as spiritual creatures, like ghosts and wraiths, popped out of the earth like in old zombie movies.
David's skin paled by the second, both because his mana was drastically drained and because his undead appearance transpired a bit more as he used a skill from his legacy.
Geminae didn't budge a single muscle as the army grew monstrously. He just stood and waited.
The ground stopped rumbling after thirty seconds, and over two hundred undead of all kinds already surrounded David. But Geminae was still unfazed.