Devoted Combo wants to chain mana from Devoted Druid, Delighted Halfling, and Leyline of Abundance into Green Sun's Zenith or Nature's Rhythm for a big payoff like Craterhoof Behemoth. Damping Sphere taxes their spell-heavy turns by making each additional spell cost more, slowing down a combo turn where they're trying to chain multiple cheap spells together. Pithing Needle can lock down a critical repeatable engine piece like Devoted Druid's untap ability or Duskwatch Recruiter's activated ability, disrupting their mana or card selection. Inquisition of Kozilek is weaker than Thoughtseize since their true combo pieces (Devoted Druid, Green Sun's Zenith) are all 2 mana or less anyway, so the swap is about trimming the least impactful discard copy for more proactive disruption; Shadowspear doesn't meaningfully interact with their combo plan.