Ragavan is in four times as many Commander decks as Jin-Gitaxias is, they are even in the same Collector Boosters, and have the same number of serialized versions
It's both hard to find a match between card and alternative cost and there are a limited number of alternative costs that work
Well, read on, as I answer both of those questions and much more

Kenrith, Kindred Princes | Commander | Stephen Johnson Commander (1) 1 Kenrith, the Returned King Creatures (27) 1 Clement, the Worrywort 1 Dour Port-Mage 1 Dreamdew Entrancer 1 Flubs, the Fool 1 Glarb, Calamity's Augur 1 Great Whale 1 Grolnok, the Omnivore 1 Haze Frog 1 Helga, Skittish Seer 1 Jade Avenger 1 Lilysplash Mentor 1 Long River Lurker 1 Octomancer 1 Palinchron 1 Peregrine Drake 1 Poison Dart Frog 1 Pollywog Prodigy 1 Rampant Frogantua 1 Spore Frog 1 Tatsunari, Toad Rider 1 Thalia and The Gitrog Monster 1 The Gitrog, Ravenous Ride 1 Three Tree Scribe 1 Twenty-Toed Toad 1 Valley Mightcaller 1 Yargle and Multani 1 Yargle, Glutton of Urborg Instants (12) 1 AEtherize 1 Aetherspouts 1 Arcane Denial 1 Counterspell 1 Fierce Guardianship 1 Heroic Intervention 1 Jaheira's Respite 1 Kindred Summons 1 Polliwallop 1 Polymorphist's Jest 1 Rapid Hybridization 1 Turn to Frog Sorceries (8) 1 Camaraderie 1 Croaking Counterpart 1 Cultivate 1 Kindred Charge 1 Kindred Dominance 1 Kodama's Reach 1 Rampant Growth 1 Shamanic Revelation Enchantments (8) 1 Amphibian Downpour 1 Frog Tongue 1 Frogify 1 Guardian Project 1 Kindred Boon 1 Kindred Discovery 1 Rhystic Study 1 Shared Animosity Artifacts (6) 1 Arcane Signet 1 Ashnod's Altar 1 Chromatic Lantern 1 Chromatic Orrery 1 Phyrexian Altar 1 The Great Henge I decided to lean way into my theme this week, playing Rapid Hybridization because it makes a Frog Lizard token, but eschewing cards like Pongify, Swords to Plowshares, and Path to Exile for not being froggy enough

Creature - Gorgon Sisters of Stone Death : Target creature blocks Sisters of Stone Death this turn if able
While later turns may be less costly for your opponents, having to do away with any previous cards youre holding makes taking on Belle a very difficult decision