I am trying to break an Ore Deposit on the ceiling I found while exploring the depths below Death Mountain. I tried to break it with a bomb arrow, but the bomb exploded in my face due to the heat before I could shoot.
How do I break an Ore Deposit on the ceiling in extreme heat if I can't use bomb arrows?
Fusing certain items adds a hammer-like property to arrows. In the case of those ceiling deposits, they are guarded by Horriblins. Horriblins drop hammer-shaped horns that will break the ore node when hit.
When I was testing around this, Moblin horns also work (and I had many more of them). Hitting the ore node will destroy the fused material, but if you miss you can go and pick it back up. Finally, this solution should almost always be available: bows and arrows seem abundant, and the material required can be harvested from the monsters guarding the nodes.
Fuse a Zonai Cannon with a melee weapon, and you get an exceedingly dangerous cannon on a stick!
What is less obvious, is that this combination overrides the normal "Throw Weapon" mechanics -- you can use R to bring up and aim the "Throw" interface as normal, but rather than releasing the weapon, you'll simply fire off a cannon shot in the aimed direction -- including towards the ceiling.
Be careful though, it takes about a full battery's charge per shot!
Major plot spoiler to answer your question:
Yunobo can be shot into the ceiling when you explore with him while chasing Zelda to Death Mountain.
Apart from @ahsteele's answer, another major plot spoiler to do the same:
Riju's avatar can shoot a thunder strike at any location (within her range) you shoot with an arrow.
You unlock this avatar by finishing the Gerudo Cataclysm quest line.
Otherwise, I suppose you can craft a vehicle from Zonai gadgets to reach the ceiling, for example with a cart (or Sled) + Balloon + Flame Emitter combo
cart. Edited.
You can fuse any item with the hammer trait, such as a Horriblin or Moblin horn, to your weapon, and then throw your weapon at it (this is a situation where long throw is helpful).
As @Gelzibar suggests, fuse something to your arrow.
And since I don't want to waste precious materials, the best item for this situation is the Zonai Portable Pot, which has the "hammer" effect and allows you to destroy Ore deposits and also cracked rocks.
Everybody has plenty of them having no practical way to use them.
Yet another plot spoiler:
While inside Sidon's Water Wall, bomb arrows will not explode in your face.
