Oko's abilities are very strong and flexible, and its low casting cost and cheap loyalty costs made it scarily aggressive
Scalable and/or X-spells are also great inclusions for decks that generate a lot of mana, as a late-game Crackle with Power, Burn at the Stake, Comet Storm or Urza's Rage can dish out such mighty degrees of damage that even Commander players quake in fear
MTG Sleeves Officially licensed from the artist WolfSkull Jack
The deck has fallen off since then, though, as Historic has gotten much more powerful over time
While there are a few cards like this, Gemstone Caverns is the only land that has this trait, and is one of the ways that players can win on the very first turn of the game under admittedly very specific circumstances
at any rate Tyvar's certainly one of the best commanders from Duskmourn