Trigon of Rage and Trigon of Infestation are of course standouts
Any non-equipment artifact and non-aura enchantment you have that has a mana value of 4 or more become a 4/4 elemental with indestructible, haste, and whenever they hit a creature, you draw a card
Per credit card
This is thanks to its first attack, Vengeance Fletchling, which initially deals 70 damage, but adds 10 more damage for every ancient card in the player's discard pile
Otherwise, its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle. In essence, this is a ramp spell that can also be used to destroy problematic artifacts or enchantments, and thats a really interesting bit of design, and well worth picking up for your decks