Exiling dredgers is the risky line, especially since Cathartic Reunion can create something from nothing, so most of the time I would look to target their Narcomoebas and Bloodghasts, thereby stranding Prized Amalgam in the graveyard
Weaker basics generally are +10, Stage 1s are generally +20, and Stage 2 are generally +30

Cait Sith, Fortune Teller Capricious Sliver Case of the Burning Masks Caves of Chaos Adventurer Chandra, Flameshaper Charforger Chase Stein, Runaway Cleon, Merry Champion Commander Sofia Daguerre Compleated Conjurer Cori Mountain Monastery Count on Luck Court of Locthwain Crimson Caravaneer Crimson Operative Cunning Rhetoric Daredevil, Man Without Fear Dark-Dweller Oracle Dogmeat, Ever Loyal Duchess, Wayward Tavernkeep Elemental Mascot Elkin Bottle Emberheart Challenger Embodiment of Flame Endrider Spikespitter Equilibrium Adept Experimental Synthesizer Fire-Brained Scheme Fireglass Mentor Fires of Mount Doom Furious Rise Galvanic Relay Geistflame Reservoir Ghost-Spider Gila Courser Gloria, the Great Armorer Goblin Researcher Grotag Night-Runner Gwen Stacy Harnesser of Storms Hedron Detonator Heroes' Hangout Hidetsugu, Devouring Chaos Hotel of Fears Intet, the Dreamer Inti, Seneschal of the Sun Irascible Wolverine Ire Shaman Jaya, Fiery Negotiator Junk Jet Junktown Kami of Celebration Kellan, Planar Trailblazer Kulrath Zealot Laelia, the Blade Reforged Lightning, Security Sergeant Magmatic Channeler Mind's Desire Mishra's Research Desk

: Add one mana of any color that a Gate you control could produce
Once per turn, it can send 1 Dragon Monster from the Hand and 1 from the Deck to the Graveyard to Banish a card in either player's Graveyard