Aethertorch Renegade: [Category 2] ETB yield is 4 Energy for 3 mana, then you can spend 2 Energy to deal 1 damage to target creature
Vindicate Obviously Vindicate at number one, one of the greatest ever gold spells
Magic cards 3 for each ornament cutting mat & rolling cutter OR ruler, pencil and scissors scissors string, yarn or embroidery floss large sewing needle [optional] black or coloured permanent marker 6
from the Fallout Universes Beyond set, it could benefit from a few extra synergy pieces but it's a good introduction to energy, and fits Aetherdrift's focus on speed and machinery well
Other cards I can see being extremely useful are the Gods from Amonkhet
Finally, cards like Illusionist's Bracers and Sting, the Glinting Dagger make Krenko's activated ability easier to use, creating an astonishing number of Goblin tokens in just one turn