enpc That sounds like a good idea, i'll try to get more vents/strands. Also, Stubborn Denial has worked wonderfully, it allows me to both counter people best if i have a Kiln Fiend, pumped nivmagus, or played many spells in one turn. I can also use it to counter my own instants and sorceries and i can eat it with nivmagus and it doesn't resolve, which allows me to do things like Warlord's Fury to Stubborn Denial to Lightning Bolt, then I can eat denial and either spell to give nivmagus 4 counters while also simultaneously pumping my other prowess creatures, kiln fiend, or dealing 6 damage with Guttersnipe. I can do larger combos like that if I have two denials, but usually i can only do three cards at once. Overall, it's been very useful.

ok SO it's looking better, but definitely still needs some changes. Correct me if I'm wrong but it looks like you're new to competitive modern and deckbuilding (no offense intended. I built a lot of bad decks before I built any coherent decks) so I'll go back to a little bit of the basics l. The sideboard should NOT be cards that just aren't good enough to be in the mainboard. All sideboard cards should be for making certain matchups better. For example, Kiln Fiend and Nivmagus Elemental being met with an opposing Fatal Push, Lightning Bolt, or Path to Exile can be game-losing. To prevent this from happening, sideboard cards like stubborn denial, spell pierce, and apostle's blessing work great! Many of the cards in your sideboard don't perform that duty (desperate ritual, Mutagenic growth). Stubborn Denial is a great card but apostle's Blessing is better in your deck; I would have 0-2 in the mainboard and 1-2 in the side (Apostle's Blessing is pretty amazing as a 1 or two of mainboard due to the fact that it deflects removal and makes the creature unblockable to the chosen color). Also, the omission of Mutagenic Growth is definitely a mistake. It's a free spell which is exactly what your deck wants. Easy 4 of. Manamorphose is a must-have for the same reason. Crash Through and Warlord’s Fury are ok since they draw a card, but Distortion Strike is way better and basically draws you a card since it's 2 in 1. You have too many creatures too. Guttersnipe is too much mana, Soul Scar Mage and Swiftspear are too many creatures. Kiln fiend is your best card, so not having 4 is weird. Thing in the ice, Nivmagus, and Kiln fiend should be your 12 creatures.