Blood offering

Using a vile of the caster's blood you can spread it across your hands and shove them in front of you, giving any undead under your control +5 temporary health. 

If you have no files of blood then you can use a one handed bladed weapon to stab into your arm to cast. This will do 1d4 piercing damage to the caster.

At higher levels: the temporary hit points of undead increase by 5 for every level above 2nd. Although the caster must choose to deal damage to themselves and not use a vile of blood. Add 1d4 piercing damage for every level above 2nd