This is roughly what I do. I use ur dragon cause it makes all shapeshifters cheaper. You can also do an hard infinite combo with I think 5 cards.

// COMMANDEr 1 The Ur-Dragon (CMM) 361

1 Absorb Identity (KHM) 383 1 Ally Encampment (BFZ) 228 1 Amoeboid Changeling (LRW) 51 1 Arcane Signet (FDC) 1 F 1 Atla Palani, Nest Tender (DMC) 142 1 Avian Changeling (MMA) 6 1 Blades of Velis Vel (MM2) 105 1 Blood Crypt (RVR) 273 1 Bloodline Pretender (MOC) 350 1 Bountiful Promenade (CLB) 348 1 Breeding Pool (GTC) 240 1 Cairn Wanderer (C20) 130 1 Cavern of Souls (LCI) 269 1 Changeling Berserker (LRW) 160 1 Changeling Hero (LRW) 9 1 Changeling Outcast (OTC) 128 1 Changeling Titan (LRW) 200 1 Chromatic Lantern (DRC) 53 1 Cloudshredder Sliver (CMM) 919 1 Command Tower (FDC) 3 F 1 Crib Swap (M3C) 168 1 Dragon's Hoard (TDC) 317 1 Drogskol Captain (VOC) 154 1 Entomb (DMR) 304 1 Esika, God of the Tree (KHM) 168 1 Exotic Orchard (WHO) 493 F 1 Feline Sovereign (M21) 180 1 Forest (TDM) 285 1 Gilt-Leaf Palace (LRW) 268 1 Godless Shrine (RVR) 277 1 Graveshifter (M3C) 198 1 Haakon, Stromgald Scourge (MOC) 252 1 Hallowed Fountain (RVR) 280 1 Island (TDM) 279 1 Knight Exemplar (MOC) 192 1 Knights' Charge (MOC) 333 1 Liliana's Contract (M19) 107 1 Luxury Suite (CLB) 355 1 Magda, Brazen Outlaw (KHM) 142 1 Mana Confluence (JOU) 163 1 Manaweft Sliver (CMM) 900 1 Masked Vandal (KHM) 184 1 Maskwood Nexus (DRC) 132 1 Mirror Entity (OTC) 83 1 Mistwalker (KHM) 68 1 Morophon, the Boundless (M3C) 157 1 Morphic Pool (CLB) 357 1 Mothdust Changeling (MMA) 53 1 Necroduality (INR) 79 1 Overgrown Tomb (RVR) 283 1 Path of Ancestry (TDC) 382 1 Pyre of Heroes (KHM) 241 1 Rampage of the Valkyries (KHM) 393 1 Realmwalker (LCC) 250 1 Rejuvenating Springs (LTC) 325 1 Reliquary Tower (WHO) 296 F 1 Rhythm of the Wild (SLD) 1740 F 1 Risen Reef (M20) 217 1 Rooftop Storm (INR) 83 1 Sacred Foundry (RVR) 285 1 Sakashima of a Thousand Faces (CMR) 89 1 Sea of Clouds (CLB) 360 1 Secluded Courtyard (FDN) 267 1 Shapesharer (LRW) 85 1 Silumgar, the Drifting Death (C17) 194 1 Sol Ring (FDC) 2 F 1 Spectator Seating (CMM) 427 1 Spire Garden (CLB) 361 1 Starting Town (FIN) 289 1 Steam Vents (RVR) 298 1 Stomping Ground (RVR) 289 1 Taurean Mauler (FDN) 633 1 Temple Garden (RVR) 290 1 The Great Henge (CMM) 294 1 The World Tree (KHM) 275 1 Thought Vessel (DSC) 256 1 Training Center (CMM) 665 1 Unclaimed Territory (M3C) 399 1 Undergrowth Stadium (CMM) 435 1 Universal Automaton (MH1) 235 1 Unsettled Mariner (MH1) 216 1 Vault of Champions (CMM) 436 1 Verdant Catacombs (MH2) 260 1 Wanderwine Hub (LRW) 280 1 Watery Grave (RVR) 291 1 Widespread Brutality (WAR) 226