Gruul Ponza plays land destruction like Mwonvuli Acid-Moss and Thermokarst backed by ramp creatures such as Arbor Elf and midsize threats like Avenging Hunter and Boarding Party, so Breath Weapon's 2 damage to each non-Dragon creature can wipe out their mana dorks and small Eldrazi Spawn tokens to slow their ramp. Cast into the Fire also picks off Arbor Elf or an Eldrazi Spawn token for tempo, or exiles a problematic artifact. Sneaky Snacker is too slow against their ramp-into-big-threats plan, so it comes out. Race aggressively with your burn suite since Ponza's land destruction can disrupt your own mana, making a fast clock important.