Deoxys V itself is a great card that punishes your opponent for building up their energy its Psychic Edge attack (costing one Psychic Energy, one Colorless Energy) does 30 HP damage, plus an extra 30 for each energy card attached to their Active Pokemon
Willowdusk can turn that lost life into a mountain of +1/+1 counters, while Rowan can give you a massive discount on black or red spells for the rest of the turn
Miara is a two-mana black Elf Scout that serves as a great Elf-tribal and Aristocrats hybrid commander, allowing you to pay one mana whenever another Elf dies, causing you to lose one life and draw a card in the process
Convoke things, sac the convokers, and go
Hamza is all about making creatures bigger using +1/+1 counters, and then casting even bigger creatures using very little mana
The benefit of getting +1/+1 counters is the plethora of support cards that provide extra counters when they are put on a creature