Exploding frogs are coming to Diablo 4 in its upcoming witchcraft season where you can summon an army of these poisonous little guys

pcgamer.com:

Frogs aren't the first thing that comes to mind when I think about Diablo 4, but that might change with its upcoming season of witchcraft where you can summon a whole army of them. They're quite messy, smacking enemies with their poison tongues and then exploding into a green mist. Skeletons could never, which is why I suspect everyone, including necromancer players, will be clamoring to become the ultimate frogmancer.

Blizzard spent a small portion of its recent stream going over the new seasonal witchcraft powers coming with season 7 in January. The exploding frogs are one of several spells you can find and upgrade throughout the season, much like season 2's vampiric powers. A shambling new enemy type, called the Headrotten, have invaded Diablo 4's open world and slaying them helps fill out your spellbook.

The existing Grim Favors system, which sends you out into the world to complete short objectives for a cache of loot, will be the focus of the season. Various regions will be taken over by Headrotten for you to hunt down and earn a new currency to spend at an expanded settlement at the base of the Tree of Whispers—something players have wanted for a while now. Blizzard says season 7 is a big experiment for what the Grim Favors could look like in the future.

There are of course more spells than just the exploding frogs, including:

Skip to 54:04 to see the frogs.

A bigger list is available in the blog post. Every spell gains a bonus effect at its maximum level, and they're designed to offer a broad benefit that everyone can utilize, like a flat damage increase or extra movement speed. Blizzard plans on going into more detail closer to the launch of the season, but the way you manage your powers looks like an iteration of the UI that was introduced with season 3's robot spider companion. Spells have tags just like skills and have a bunch of synergies for combining different types.

Several of these new powers will be in the upcoming public test realm version of the