While the flavor there is awesome, that is certainly a frustrating restriction
Cards like Old Gnawbone can help you use the buffed creatures to generate even more mana, synergizing with the +1/+1 counters
Factions which suggested mechanical themes that would be fun and easy to implement should be preferred over ones that didn't
When combined with other burn spells, Thermo-Alchemist can deal devastating amounts of burn damage, while also having good toughness to act as a blocker for low-power threats
However, depending on its specific effects and mana cost, there may be better alternatives available, such as cards that offer more immediate impact or synergy with the current meta, like Teferi, Hero of Dominaria for control decks or Tarmogoyf for midrange strategies
Titan of Industry We keep up with the ETB theme in titans with Titan of Industry from Streets of New Capenna