This is a really, really fun deck that I'm excited to have gotten running pretty smoothly, even after it lost Growth Spiral and Teferi, Time Raveler. If you are a newer player reading this, I don't recommend sinking wildcards into this deck because many of these will sadly be rotating next month, including our star babies Niv-Mizzet, Reborn and Golos, Tireless Pilgrim (fun fact: he's looking for his lost brother, Solemn Simulacrum!) This deck requires two important pathways: (1) what land do you need to play, and is playing it untapped or not important. Be sure to play the land that allows you the most access to your hand. (2) knowing which bomb to pop off when Nevertheless - let's check this out!

Early Game: What's wonderful about this deck is, you can respond as needed. If you read my Junderdome deck, it has similiarties - hand removal with Thought Erasure and Kroxa, Titan of Death's Hunger and exiling said card with Klothys, God of Destiny, or permanent removal Assassin's Trophy and Justice Strike. You have Deafening Clarion in case things get wild and Angrath's Rampage for 3-drop planeswalkers. On the play, since your lands are usually tapped, you can be reactive. On the draw, you'll be draining life to ensure your threats can respond appropriately, be mindful with how you use your lands. In nothing is happening turn 3, get Jegantha, Primal Wellspring in your life!

Mid Game: Get some cards in with Atris, Oracle of Truths (a personal favorite of mine), set-up with Faeburrow Elder, or keeping playing defensively with Deputy Detention. Like the early game, follow what your opponent is doing - YOU are the master of all magics in a rainbow deck! Remember you can use Klothys, God of Destiny to help you fix or ramp in a bind, if your opponent has lands in the graveyard, this may allow you to play a triome tapped while still churning out threats, which is solid.

Late Game: The fun part! I personally like a turn 5 Golos, Tireless Pilgrim first because you can grab a triome with his ability. This can also set you up for activating his 2WBURG ability the following turn. If you dumped your hand out from aggressive removal, go ahead and cast Niv-Mizzet, Reborn! You get to look at 10 cards in your deck, and you're likely at around 45 cards when you cast him, so you're seeing almost 25% of your possible threats and/or answers! Pick what you need - remember his stipulation though. If you're playing around countermagic, I would let Jegantha get countered, because Niv is that much better.

Strengths: Midrange decks are just completely outclassed by this deck. Control decks can't hurt you with draw punishment (Underworld Dreams or Ob-Nixilis, The Hate-Twisted) or draw disallow Narset, Parter of Veils since Niv's ability is "put". Since you have Niambi, Esteemed Speaker you can re-cast Niv when you need cards (lol) or even 5 life. She's been great to save Niv from kill spells while restoring 25% of your starting life.

Weaknesses: Heavy aggro or decks that utilize Stonecoil Serpent or Basri's Lieutenant. Hand hate against you can also cut you off from possible spells you can cast. 

Sideboarding Tips: Color hate because you have access to so much. I honestly rarely board with this deck.

Rotating Tips: This deck is not surviving :(.