I am looking to pair Hammerskull with cards like The Great Henge, Fight Rigging, Volcanic Salvo, etc
Expend Hey, if picturesque vistas and adorable denizens guaranteed safety, we'd have time for more games, but we have to put a little work in, you know
Brought Back (Core Set 2020) 2 mana to quickly retrieve any 2 permanents that went to the graveyard from the battlefield this turn is quite good
Then, when they enter the battlefield, either each other Creature gets -X/-X until the end of turn, and you lose X life, or you can return up to X Creature cards with a mana value of X or less from your graveyard to the battlefield, and then give them haste until the end of turn
The other one is more of a combo, where you use some counter shenanigans to accelerate loyalty totals until you can suddenly ultimate five planeswalkers in a single turn
Slow decks want engines and bombs, while aggressive decks want evasion and card advantage