Houndoom’s Mega Stone (Houndoominite) can be found near the hot springs in Lavaridge Town. You’ll find the Mega Stone on the left side of the town just below the hot sand bath area & just above the gym.
However, you can only find it there after you defeat/catch Kyogre or Groudon in the Cave of Origin.
Houndoominite Location (Step-by-Step)
Most Mega Stones, including Houndoom’s Mega Stone, are only obtainable after you defeat/catch Kyogre or Groudon in Sootopolis City; more specifically, in the Cave of Origin. This major event happens right before you’re able to challenge the eighth and final Gym.
For the Mega Stone’s exact location, start by flying back to Lavaridge Town’s Pokémon Center after the Cave of Origin event.
Step 1: Turn left and make your way toward the rocky wall on the left side of town (just past the hot springs).
Step 2: You should see a sparkling item in the lower-left corner of this rocky area. Interact with it to obtain the Houndoominite.
Is Mega Houndoom Good?
Mega Stones, like the Houndoominite, are held items that allow certain Pokémon to Mega Evolve, granting them a massive boost to their base stats.
Most Mega Evolutions also change the Pokémon’s ability, which lasts until the battle concludes.
When Houndoom Mega Evolves into Mega Houndoom, it changes its ability to Solar Power, which increases the user’s Special Attack by 50% during harsh sunlight. However it loses 12.5% of its max HP at the end of each turn.
Mega Houndoom also receives boosts to its Special Attack and Speed, making it a formidable offensive sweeper.
A Fire Blast empowered by the sunny weather and Solar Power is sure to deal a ton of damage.
With its new ability Solar Power, Mega Houndoom is now especially good in Sun teams. The extra boost Solar Power gives makes this Mega evolution a monstrous wallbreaker. Sun teams also give Mega Houndoom access to a one-turn Solar Beam, which is sure to knock out plenty of Water-type threats.
Houndoom’s low Defense stat is also remedied upon Mega Evolution, giving it the ability to survive more Physical attacks.