Polar Bear

A polar bear ally is a druid's wild shape, the bond-beast of an arctic ranger, or a cub the party rescued that has grown up alongside them. A wild polar bear does not befriend humanoids, but a hand-raised one will defend its pack to the death.

In combat, run the bear as the front line. Rend at +7 doing 1d8+5, Multiattack two Rends per turn. 42 HP and AC 12 mean the bear can hold a chokepoint for two or three rounds against tier-1 enemies. Use it to plug doorways the rogue is unlocking behind, or wade into the river and pin the goblin canoe so the ranger can shoot.

Out of combat, the polar bear is a heavy that lives in the cold. Walk 40, swim 40, and Cold Resistance let it cross winter terrain the party would otherwise need rope and pitons for. Use it as search-and-rescue: Perception +5 and the bulk to break thin ice let it find a PC who fell through and dredge them out.

The bear eats a lot and does not enter buildings smaller than a temple. Plan for the scenes where it waits outside, and have it greet the party at the gate when they return, having killed and eaten something the gatekeeper now wants compensation for.

A polar bear is a CR 2 ambush in the snow, and the ambush is the encounter. Stealth +4, Perception +5, white fur on white tundra. The party walks past a snowbank and the snowbank stands up. 42 HP, AC 12, Strength 20, Multiattack is two Rend attacks at +7 doing 1d8+5 slashing each. Cold Resistance means half damage from ice and freezing.

The bear opens with a charge. Walk 40, swim 40 means it is faster than the party in winter terrain that matters. Round one is a Rend on the closest PC; on a hit the bear commits to that target. The bear does not switch unless its current meal is dead. This is what makes a polar bear scary: it commits and does not recalculate.

Use terrain. A fight on frozen lake is different than a forest. Roll thin ice: DC 12 Strength save when the bear charges across, fall through on a failure, then spend a turn climbing back up while the bear circles in the water. The party not prepared for cold-weather adventuring learns the difference between adventuring gear and survival.

A polar bear retreats once bloodied and the prey is fighting back. It is a predator, not a soldier. Have it back off, climb a snowdrift, and watch from cover. The party should know it is still up there. The next watch should hear it breathing.