Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Collect Dragon's Breath in a Glass Bottle.

Kill a Mob while wearing the same type of Mob Head.

Kill a creeper with Arrows.

Win 3 rounds in a row after one of the opponents has won 2 rounds.

Win a Tumble game whilst on the lowest layer in a Snowball Tumble Mini Game.

Win a single round of Snowball Tumble without throwing any Snowballs.

Hit a single Player with 25 Snowballs in a single public round.

Take 100 damage in a round of a public Battle game.

Swim in lava while having the Fire Resistance effect.

Cook and eat a pork chop.

Relieve a Blaze of its rod.

Build some bookshelves to improve your enchantment table.