Devoted Combo wants to chain Devoted Druid and Green Sun's Zenith into a fast combo kill, and while Mystical Dispute doesn't get discounted against their green spells, it's still a flexible tax effect that can stop a critical Green Sun's Zenith or Nature's Rhythm for 3 mana if they can't pay. Surgical Extraction can strip a copy of Devoted Druid from their graveyard to thin their redundancy. While Lightning Bolt can destroy Devoted Druid (3 damage is lethal against the 0/2), larger threats like Craterhoof Behemoth aren't answered by 3 damage and Agatha's Soul Cauldron is an artifact that can't be targeted by damage, and Cling to Dust doesn't meaningfully disrupt their engine, so both trim down for more proactive interaction and Counterspell/Spell Snare backup already in the mainboard.