Going back to just hefty loot today, since we've been doing high end stuff for a few weeks now. This is a non-engineer explosive that packs about as big a punch as you're going to get.

Name: Crystal Charge (Wowhead, Thottbot, MMODB)
Type: Consumable
Damage/Speed: N/A (See below)
Abilities:

• Use: Inflicts 383 to 517 fire damage in a three yard radius.
• Does not require an engineer to throw, although it is consumable. And I'll make another extreme statement (even though, like I said last week, you wily commenters usually prove me wrong): this is the most damaging non-Engineer thrown consumable. The Essence of Eranikus actually does more damage over time, but it's a trinket, and this is the highest damage non-Engineer grenade that I could find.
• And, dear readers, I actually went into the game and did a little playtesting with this stuff just for you. Unfortunately, I have to report that it does not add spell damage (I wasn't surprised by that, but I can confirm that it doesn't).
• But it does in fact crit-- I had one of my charges break 575. And I also used it on multiple targets, so if you can fit more than one thing in the (small) 3 yard radius, you can hit them all with ~400+ fire damage.

How to Get It: As you may have guessed, it's part of the Un'Goro Crystals setup. To start collecting and using crystals, you have to do the chain offered by J.D. Collie at Marshal's Refuge there. He'll show you how to get the crystals and the spires you'll need to take them to. And once you've finished all his Fedex-ing (it's easy enough to do if you're leveling through Un'Goro around the early 50s anyway), you'll be able to get a quest from the Northern Spire itself called Crystal Charge.

That quest requires that you grab 10 Red Power Crystals and 10 Yellow Power Crystals from the deposits around Un'Goro. Bring those back (or just bring them along-- you don't need the quest to collect the crystals, and you might even find them on the AH if someone on your server is trying to clean out their bags), and you'll get 6 Crystal Charges for each turn-in of 10.

Getting Rid of It: Sells to vendors for 10s. While the Power Crystals themselves are BoE (or at least not soulbound), the Charges are BoP, so sell them or use them.