What makes [c]Chord of Calling[/c] so strong though, is that it has convoke, allowing you to tap creatures for extra mana
Three mana identity keeps it back in my 6-spot, but I do love it loads at the kitchen table in loads of places like Five Color and Type Four

Tymna the WeaverTymna the Weaver Ragavan, Nimble PilfererRagavan, Nimble Pilferer Purphoros, God of the ForgePurphoros, God of the Forge Kinnan, Bonder ProdigyKinnan, Bonder Prodigy Winota, Joiner of ForcesWinota, Joiner of Forces Azusa, Lost but SeekingAzusa, Lost but Seeking Jodah, the UnifierJodah, the Unifier Muldrotha, the GravetideMuldrotha, the Gravetide Gix, Yawgmoth PraetorGix, Yawgmoth Praetor Kraum, Ludevic's OpusKraum, Ludevic's Opus Ishai, Ojutai DragonspeakerIshai, Ojutai Dragonspeaker Bruse Tarl, Boorish HerderBruse Tarl, Boorish Herder Adeline, Resplendent CatharAdeline, Resplendent Cathar Inalla, Archmage RitualistInalla, Archmage Ritualist Godo, Bandit WarlordGodo, Bandit Warlord Sram, Senior EdificerSram, Senior Edificer Varragoth, Bloodsky SireVarragoth, Bloodsky Sire Mangara, the DiplomatMangara, the Diplomat Loran of the Third PathLoran of the Third Path Venser, Shaper SavantVenser, Shaper Savant Of course, all this means nothing if you're really, really excited to get your hands on the Final Fantasy'd version of your favorite commander

Considering its one half of an infamous two-card combo, its no wonder theres a good deal of demand
In go-wide and tribal strategies , Mirrorform shines by converting token swarms or low-power tribes into legitimate finishers without committing to permanent buffs