Added in the April 9th update, a debuff occurs when a different biome animal enters another biome. For ocean/land biome animals, if they enter the arctic they get frozen for the amount of the the Yeti freeze lasts. If the arctic biome goes out of the arctic into ocean/land biomes, instead of freezing they burn for how long the dragon fire lasts.
It was added in the April 9th update, along a lot of other very cool stuff, including Black Dragons, etc.
It is the only thing that can damage you without the need of a projectile or an animal.
Freeze is a status effect that happens when hit by Yeti, Mammoth etc's ability. This effect also occurs when going into the arctic when not an arctic animal. There used to be a glitch when touching a healing stone and being frozen at the same time will instantly kill you, at any tier animal. Whether if its a Yeti and a mouse, or a Yeti and a Black Dragon. The effect slows you down. I think that this effect is slower than stun. It also does a fair amount of damage. (Very little) This is oftenly used for escape or chase.
Burn is a status effect that occurs if a Dragon/Black Dragon throws fire on you or if you go into lava. It is one of the more deadlier effects as it does the same amount of damage as Freeze then does more damage over time, potentially killing you if you do not reach water. If you reach water the burn will go away. There used to be a time where burn was very overpowered as it burned you while you were in water and even diving under water, giving Dragons an easy way to kill Krakens. Even with the nerfed fire effect, it is still easy to kill Krakens with Dragons.
Stun is a status effect inflicted by most abilities. Stun acts similar to freeze except it does not deal damage. It slows down movement speed and is used for escape or to chase someone. This seems to be slower than freeze. (Needs work)
Thirst is one of the most deadlier debuffs as it will kill you unless you get water. It quickly drains away health and does not end until you get water. (Needs work)
Heat is not a confirmed effect, but it happens when you're in the lava biome. If your in the lava biome with any animal other than Black Dragon, you're thirst bar will go down drastically. (Needs work)