At 10th level you have learned that you can reabsorb the magical energy used to animate an undead creature, allowing you to gain spell slots equal to level of the spell used to animate the sacrificed creature.

due to the increasing negative energy of the Elder Lich any being touched by the lich will receive 1d4 Necrotic damage beginning at level 5. at the start of its turn, the elder lich can also choose to 'Charge' their negative energy. for each turn that the elder lich charges this ability it will deal an additional 1d3 necrotic damage. beginning at level 10 the elder lich can temporarily go past their limits and exert a huge amount of negative energy, in this state the lich may fire a negative energy burst that deals 5d8 + 1d12 Necrotic damage.   

You can see in all darkness up to 60/120ft and can see past invisibility and illusion magics

Compelled by the power of an Elder Lich lesser undead will follow the commands of a Elder Lich. Any undead that have a challenge rating of less than 1/2 the elder lich's level must follow its commands. the lich may attempt to control higher challange rated undead but they can resist should they succeed a DC 10 int check.

Bonus to intelligence checks

The Elder lich take additional damage when hit with radiant damage equal to half rolled damage.

When you cast a necromancy spell you gain a bonus to your roll (1D6 + your total spellcasting level). Starting at 5th level when you cast a necromancy spell that would result in the creation of an undead you can overcharge the spell allowing you to create a more powerful undead but only if you roll above a DC 15 Arcana check. if the check is failed then the spell shall result in a random effect determined by the wild magic surge chart.