So I Got That Going For Me...

Lead a Caravan containing at least 5 Llamas.

Castaway

Eat nothing but Kelp for 3 days.

Sleep with the Fishes

Stay underwater for one full day without using potions.

1 Pickle, 2 Pickle, Sea Pickle 4

Place four Sea Pickles in one block.

Moskstraumen

Activate a Conduit.

Echolocation

Bribe a Dolphin.

Alternative Fuel

Use a Dried Kelp block as fuel in a furnace.

'Tis but a scratch

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

Snowplough

Push three Players into Lava using Snowballs.

Mine!

Open every chest in a Battle mini game arena in one round.

Cupid

Kill 2 players in a round of a public Battle mini game using a bow and arrow.

...has become the master

Win 3 public Battle games in a row.

Hunger Pain

Kill a player while you are starving in a Battle mini game.

Great View From Up Here

Levitate up 50 blocks from the attacks of a Shulker.

The Deep End

Defeat an Elder Guardian.

Let It Go! 

Walk across the surface of a deep ocean by freezing the water with Frost Walker boots. 

Underdog

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

Hotshot

Hit a Player with a Snowball while falling into the Lava.

Back from the Dead

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

Snow Storm

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

Overlord

Stay on the top layer while winning a round in a Snowball Tumble Mini Game.

S-No Throw

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

Taste of Your Own Medicine

Poison a Witch with a Splash Potion.

The End... Again...

Respawn the Enderdragon.

Super Sonic

Use an Elytra to fly through a 1 by 1 gap while moving faster than 40 m/s.

Map Room

Place a fully explored Map into an Item Frame.

You Need a Mint

Collect Dragon's Breath in a Glass Bottle.

Beam Me Up

Teleport over 100 meters from a single throw of an Ender Pearl.

Free Diver

Stay underwater for 2 minutes.

Dry Spell

Dry a Sponge in a Furnace.

Camouflage

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

Super Fuel

Power a Furnace with Lava.

Saddle Up

Tame a Horse.

The Student...

Win a public Battle mini game.

The Beginning.

Kill the Wither.

The Beginning?

Spawn the Wither.

Overpowered

Eat a Notch Apple.

Tie Dye Outfit

Dye all 4 unique pieces of Leather Armor.

Trampoline

Bounce 30 blocks upward off a Slime Block.

Beaconator

Create and fully power a Beacon.

Passing the Time

Play for 100 days.

Adventuring Time

Discover 17 of the 40 different biomes.

Zombie Doctor

Cure a Zombie Villager.

Overkill

Deal nine hearts of damage in a single hit.

The Haggler

Mine or purchase 30 Emeralds.

Return to Sender

Destroy a Ghast with a fireball.

The End.

Kill the Enderdragon.

The End?

Enter an End Portal.

Pot Planter

Craft and place a Flower Pot.

Sniper Duel

Kill a Skeleton with an arrow from more than 50 meters.

Chestful of Cobblestone

Mine 1,728 Cobblestone and place it in a chest.

Enchanter

Construct an Enchantment Table.

Iron Belly

Stop starvation using Rotten Flesh

Body Guard

Create an Iron Golem.

Rainbow Collection

Gather all 16 colors of wool.

Lion Tamer

Tame an Ocelot.

Stayin' Frosty

Swim in lava while having the Fire Resistance effect.

Renewable Energy

Smelt wood trunks using charcoal to make more charcoal.

Pork Chop

Cook and eat a pork chop.

Have a Shearful Day

Use Shears to obtain wool from a sheep.

Local Brewery

Brew a potion.

It's a Sign!

Craft and place a Sign.

Archer

Kill a creeper with arrows.

Iron Man

Wear a full suit of Iron Armour.

Librarian

Build some bookshelves to improve your enchantment table.

Diamonds to you!

Throw diamonds at another player.

DIAMONDS!

Acquire diamonds with your iron tools.

Into Fire

Relieve a Blaze of its rod.

Repopulation

Breed two cows with wheat.

Music to my Ears

Play a music disc in a Jukebox.

Leader Of The Pack

Befriend five wolves.

Delicious Fish

Catch and cook a fish!

The Lie

Bake a cake using wheat, sugar, milk and eggs!

Bake Bread

Turn wheat into bread.

On A Rail

Travel by minecart to a point at least 500m in a single direction from where you started.

When Pigs Fly

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

Into The Nether

Construct a Nether Portal.

Dispense With This

Construct a Dispenser.

Acquire Hardware

Smelt an iron ingot.

Getting an Upgrade

Construct a better pickaxe.

Time to Farm!

Use planks and sticks to make a hoe.

MOAR Tools

Construct one type of each tool (one pickaxe, one spade, one axe and one hoe).

Hot Topic

Construct a furnace out of eight cobblestone blocks.

Time to Strike!

Use planks and sticks to make a sword.

Time to Mine!

Use planks and sticks to make a pickaxe.

Cow Tipper

Harvest some leather.

Monster Hunter

Attack and destroy a monster.

Benchmarking

Craft a workbench with four blocks of wooden planks.

Getting Wood

Punch a tree until the block of wood pops out.

Taking Inventory

Open your inventory.

Cheating Death

Use the Totem of Undying to cheat death.

Change of Sheets 

Dye your bed a different color.

Feeling Ill

Defeat an Evoker.