Snow Balla

The Snow Balla is a Hardmode enemy that only spawns during the Frost Legion event. It throws snowballs at the player that form Snow Blocks on impact with other blocks, similar to the attack of the Antlion. The Snow Blocks can also spawn in the air if Snow Balla throws it into the sky. If it falls in a pit, it is possible for it to trap itself. By trapping the Snow Balla, one can create a renewable farm for Snow Blocks in a similar manner to the Antlion-based sand farm.

Trivia

 * "Snow Balla" is a play on words; the Snow Balla mob throws snow balls, thus it was named the "Snow Balla".
 * If the two words are combined, it is read as "Snowballa", a slang of "snowballer", which fits the description of what it does.
 * This is one of only two or three creatures besides the player that can place blocks in the world. (The other being the Antlion, and debatably the Wall of Flesh.)