The most fearsome builds of this commander Ive encountered lean heavily into artifact ramp and black board wipes like Toxic Deluge and Damnation to control the board until it overwhelms its opponents with the monsters of the deep
Flexibility, drama, and a dash of desperationjust what you need when things look grim
The Templin Institute has a great recap on her lore here: ILLUMINOR SZERAS Commander players love a Burnt Offering, a Soldevi Adnate or a Ruthless Technomancer
Due to their flexibility and ability to provide additional mana, Treasure tokens are able to help nearly any type of deck as they can simultaneously function as both mana ramp and mana fixing
A little lower in the pecking order is Goblin Chieftain , which gives all other Goblins you control +1/+1 and haste
Specific "Hate" Cards: Including cards that are designed to shut down a particular strategy, such as graveyard hate against reanimator decks or artifact removal against artifact-heavy strategies