Five-Color Niv-Mizzet
A Pioneer deck, by Patxi
1st place at a tournament in Magic Online on 2020-08-16

Maindeck:

Creatures
2 Deathrite Shaman
4 Sylvan Caryatid

Instants
1 Abrupt Decay
2 Fatal Push
1 Utter End

Legendary Creatures
1 Chevill, Bane of Monsters
4 Niv-Mizzet Reborn
1 Tolsimir, Friend to Wolves
4 Uro, Titan of Nature's Wrath (Banned in Pioneer)

Legendary Enchantments
2 Oath of Kaya
2 Oath of Nissa

Legendary Planeswalkers
2 Nahiri, the Harbinger
4 Teferi, Time Raveler (Banned in Pioneer)

Sorceries
4 Bring to Light
4 Dreadbore
1 Hour of Devastation
1 Rakdos's Return
2 Solar Blaze
2 Thoughtseize

Basic Lands
1 Forest
1 Island
1 Mountain
1 Plains
1 Swamp

Lands
1 Breeding Pool
1 Drowned Catacomb
4 Fabled Passage
2 Glacial Fortress
1 Hinterland Harbor
2 Indatha Triome
1 Ketria Triome
1 Mana Confluence
3 Overgrown Tomb
2 Rootbound Crag
2 Savai Triome
1 Stomping Ground
2 Sulfur Falls
2 Temple Garden
2 Watery Grave
4 Zagoth Triome

Sideboard:
2 Voice of Resurgence
2 Shark Typhoon
1 Abrupt Decay
2 Fatal Push
1 Chevill, Bane of Monsters
1 Yorion, Sky Nomad
1 Casualties of War
1 Slaughter Games
2 Solar Blaze
1 Thought Erasure
1 Thoughtseize