Giant Frog

A friendly giant frog is a witch's sentinel, a bullywug peace offering, a swamp druid's wild shape, or a memorable result of a Speak with Animals conversation that went somewhere unexpected. The frog does not understand strategy, but it understands the territory. Run it as a guide and a swimmer, not a fighter.

In water, the frog is genuinely useful. It can carry a Small character on its back at a 30 ft. swim, drag a rope to the far bank, or scout the bottom of a flooded crypt with darkvision 30 ft. that the party doesn't have. Stealth +4 from the waterline means it can creep up on a bullywug camp and come back with a head count. Out of water it walks 30 ft. on land but is conspicuous and clumsy, so keep it in the bog for any meaningful task.

Combat use is limited because the stat block has no attacks. If the players push, narrate a tongue-lash that knocks a torch into the water or a body-slam that interrupts a spell, and resolve it as a contested check rather than a damage roll. The frog has 18 HP and AC 11; one hit from anything serious puts it down, and the party should feel that fragility.

Have the frog answer to one specific cue: a whistle, a name, the smell of a particular bait. When the cue is gone, the frog wanders off to find food. Ally beasts work better when their loyalty has a clear off-switch the players can mourn losing.

A giant frog is an ambush from the waterline, almost never a single combatant. CR 1/4, 18 HP, AC 11, 30 ft. swim and 30 ft. walk, Stealth +4, passive 12, 30 ft. darkvision. The stat block has no listed attack, which sounds wrong until you realize the giant frog is a setup creature: it appears in twos and threes around a swamp encounter, biting at the party's ankles while the actual threat (the bullywug priest, the lizardfolk patrol, the will-o'-wisp luring them deeper) develops behind it.

Open from concealment. With Stealth +4 against most low-level passive Perceptions, the frog is a hummock of moss until someone steps within five feet. Since the SRD entry lists no attack, set a generic bite before play (1d6 or so based on the size you're picturing) and tell your players the number you're using. The real value of the frog is occupying a melee fighter in chest-deep water while the party's casters lose Concentration to the splash and the dark.

Positioning is the encounter. The frog swims 30 ft. and walks 30 ft., so it pulls a distracted PC away from the party along the bottom of a bog, and Darkvision 30 ft. lets it see in murk that blinds the rest of them. Fight in the water, in the reeds, never the open clearing.

Frogs flee. Once half the pack drops, the survivors croak once, dive, and don't pursue out of water. If you'd rather not invent damage at all, run the frog as a swallow gag: it lunges at the smallest PC, fails to swallow, and gets cleaved by the next reaction. The table laughs and the swamp keeps its mood.