Frostbitten zombies, zombie wolves, sledges and sledge jockeys

Here are some ideas for snowy biomes for the mounts of mayhem.

First, the frostbitten ! Zombie variant that spawns in snowy biomes with normal zombies. They would apply the Frost effect on hit.

Frost effect: Slows down the target by a certain percentage while doing 1 point of damage every 2 seconds. The duration could be between 10 to 15 seconds.

Second, zombie wolves ! They would only spawn attached to a sledge when a sledge jockey spawns.  Like the zombie nautilus, zombie wolves will become neutral when the rider is killed. Can be tamed with bones just like normal wolves, but can't be bred. They would drop rotten flesh on death. Unfortunately, no zombie wolf variants, because i think its a bit too much, and they're zombies anyways !

Third, the sledge ! Crafted with 4 wood planks of any type and 2 iron ingots in a crafting table (1 plank in top left or right corner, 3 planks in the middle row, and an iron ingot in both bottom left and right corner). To balance it with the boat, the ice feature from boats would be removed to be used by the sledge instead. The sledge can climb 1.1 block tall (avoid being stuck on path blocks) and would work better on snow blocks, snow layers and anything type of ice. 2 wolves could be attached onto it, making it go faster.

Sledge jockeys: a frostbitten with an iron spear on a sledge with 2 zombie wolves attached to the sledge. A pretty deadly combo !