All the Elk

Click here for visual deck (with images)
Click here for my EDH Commander decks
 
When I designed this, I had two directions I could go:
• [Smash people with fat Elk]: Elk, Changelings, Tribal stuff
• [Turn stuff into other stuff]: Elk, and "Target creature loses all abilities and becomes a ___" and "Destroy target creature, get a ___ token" effects
Both seemed funny, but unfortunately I didn't have room to do both in the same deck. I chose the former. Some of the second deck idea is shown in the sideboard.
Note that Jegantha is being played here as a general, not a companion.
 
Mana Acceleration (11): General (1): Spells (26): Sideboard (Omitted/Cut card ideas):
1 Burnished Hart 1 Jegantha, the Wellspring 1 Door of Destinies 1 Myntasha, Honored One
1 Herald's Horn   1 Icon of Ancestry 1 Mirror of the Forebears
1 Urza's Incubator Creatures (26): 1 Obelisk of Urd 1 Mirage Mirror
1 Mirari's Wake 1 Moritte of the Frost 1 Riptide Replicator 1 Mirrorweave
1 Cultivate 1 Graveshifter 1 Vanquisher's Banner 1 Oko, the Trickster
1 Dawntreader Elk 1 Shapesharer 1 Oko, Thief of Crowns 1 Irregular Cohort
1 Golden Hind 1 Wetland Sambar 1 Smelt Herd Saw 1 Cairn Wanderer
1 Jiang Yanggu, Wildcrafter 1 Auspicious Starrix 1 Cover of Darkness 1 Adaptive Automaton
1 Kodama's Reach 1 Axebane Stag 1 Crippling Fear 1 Metallic Mimic
1 Zendikar Resurgent 1 Bellowing Elk 1 Haunting Voyage 1 Chameleon Colossus
1 Mana Echoes 1 Dawnglade Regent 1 Kindred Dominance 1 Valiant Changeling
  1 Ethereal Elk 1 Patriarch's Bidding 1 Birthing Boughs
Lands (36): 1 Gang of Elk 1 Call to the Kindred 1 Infinite Reflection
1 Crumbling Necropolis 1 Great Sable Stag 1 Distant Melody 1 Polymorphous Rush
1 Arcane Sanctum 1 Highland Game 1 Kindred Discovery 1 Cytoshape
1 Savage Lands 1 Realmwalker 1 Reflections of Littjara 1 Saheeli, Sublime Artificer
1 Seaside Citadel 1 Sacred White Deer 1 Hidden Stag 1 Gallows at Willow Hill
1 Jungle Shrine 1 Saddled Rimestag 1 Jiang Yanggu 1 Elkin Bottle
1 Opulent Palace 1 Somberwald Stag 1 Kenrith's Transformation 1 Elkin Lair
1 Sandsteppe Citadel 1 Springmane Cervin 1 Kindred Summons 1 Snakeform
1 Nomad Outpost 1 Stampeding Elk Herd 1 Tribal Unity 1 Turn // Burn
1 Frontier Bivouac 1 Taurean Mauler 1 Vivien, Nature's Avenger 1 Sudden Spoiling
1 Mystic Monastery 1 Fey Steed 1 Kindred Charge 1 Deep Freeze
1 Indatha Triome 1 Glimmerpoint Stag 1 Molten Echoes 1 Fowl Play
1 Ketria Triome 1 Great Hart 1 Shared Animosity 1 Frogify
1 Raugrin Triome 1 Heliod's Emissary 1 Crib Swap 1 Gift of Tusks
1 Savai Triome 1 Mirror Entity   1 Imprisoned in the Moon
1 Zagoth Triome 1 Splendor Mare   1 Kasmina's Transmutation
1 Cavern of Souls 1 Star-Crowned Stag   1 Merfolk Trickster
1 Command Tower     1 Ovinize
1 Exotic Orchard     1 Polymorphist's Jest
1 Path of Ancestry     1 Turn to Frog
1 Unclaimed Territory     1 Vedalken Humiliator
2 Swamp     1 Very Cryptic Command C
4 Island     1 Warkite Marauder
5 Forest     1 Will Kenrith
1 Mountain     1 Song of the Dryads
3 Plains     1 Opportunistic Dragon
1 Sol Ring     1 Darksteel Mutation
      1 Humble
      1 Humility
      1 Overwhelming Splendor
      1 Reprobation
      1 Soul Sculptor
      1 Transmogrifying Wand
      1 Incubation // Incongruity
      1 Mercy Killing
      1 Sarkhan the Mad
      1 Curse of the Swine
      1 Hour of Need
      1 Pongify
      1 Rapid Hybridization
      1 Beast Within
      1 Rampage of the Clans
      1 Descent of the Dragons
      1 Mogg Infestation
      1 Afterlife
      1 Generous Gift
      1 March of Souls
      1 Basalt Golem
      1 Ovinomancer
      1 Terastodon
      1 Cavalier of Dawn