This matchup is a race between our combo and their Eldrazi ramp into Devourer of Destiny and Emrakul, the Promised End, so proactive interaction that answers their early plays is key. Abrupt Decay destroys Basking Broodscale or Glaring Fleshraker regardless of how large they grow, and cannot be countered by their Vexing Bauble. Kraul Harpooner is mediocre since they have almost no flyers, but its reach body still trades well and blocks their ground creatures, so it's a marginal add over a clunkier card. Walking Ballista and Duskwatch Recruiter are the weakest link cards against a deck that isn't attacking our life total or graveyard, so they make room. Keep the mana base fully intact and prioritize assembling Devoted Druid plus Vizier of Remedies or Nature's Rhythm into Craterhoof before they land a turn-4 Emrakul.

Izzet Prowess is an aggressive burn-based tempo deck; Abrupt Decay is uncounterable removal for Dragon's Rage Channeler, Monastery Swiftspear, or Cori-Steel Cutter before it snowballs. Fatal Push still answers most of their 1-2 mana creatures but Abrupt Decay is more flexible against their equipment and Slickshot Show-Off. Kraul Harpooner's 3/2 reach body and undergrowth trigger helps stabilize the ground and can block early aggression. We want to prioritize surviving to our combo turn, so any extra blocker/removal is valuable against this fast clock.

Boros Energy brings a swarm of cheap removal (Path to Exile, Erode, Galvanic Discharge) and sweepers (Wrath of the Skies, Avengers Disassembled), so we need to protect our combo pieces and avoid overextending into their board wipes. Drannith Magistrate prevents them from casting spells from anywhere but hand, which is relevant if they try to cheat spells in from exile (such as cards exiled by The Legend of Roku) or otherwise play around normal casting restrictions; its 1/3 body also blocks Glaring-style aggression reasonably well. Walking Ballista and Duskwatch Recruiter are the easiest cuts since Ballista dies immediately to their removal suite before doing much and Recruiter is too slow against their efficient interaction; Ouroboroid is also a marginal card here since it does nothing the turn it resolves and dies just as easily to Wrath of the Skies as anything else. Sequence combo pieces carefully, playing around Path to Exile and Erode by holding Nature's Rhythm or Green Sun's Zenith until you can protect the target or go off in one turn.