Despite how strong Yuna, Grand Summoner is, for example, she primarily creates value in archetypes centered around +1/+1 counters
No matter where she is (hand, spellbook, cemetery, your grandmas house, etc) Vivien the Enchantress has ALL printed abilities of every avatar and spellcaster in the realm
Atog deck: 25 Cards known to exist, to be completed with the missing ones: Counterspell (7th Edition) Entomb (Odyssey) Fact or Fiction (Invasion) Fire / Ice (Apocalypse) Flametongue Kavu (Planeshift) Island 332/350 (7th Edition) Island 333/350 (7th Edition) Island 334/350 (7th Edition) Island 336/350 (Invasion) Island 337/350 (Invasion) Island 338/350 (Invasion) Island 335/350 (Onslaught) Island 337/350 (Onslaught) Island 338/350 (Onslaught) Nightscape Familiar (Planeshift) Psychatog (Odyssey) Repulse (Invasion) Salt Marsh (Invasion) Shadowmage Infiltrator (Odyssey) Shivan Reef (Apocalypse) Syncopate (Odyssey) Underground River (7th Edition) Undermine (Invasion) Urborg Volcano (Invasion) Urza's Rage (Invasion) Mini MTG Cards Angry Dog Deck Uncut Sheet 10 x 11 front
The latter ability is the one that Kappa Cannoneer has, and it makes it a much more powerful threat than its initial 5U cost and 4/4 statline would make it appear to be
If your deck has black in its color identity, Secret Salvage can be a great way to fill your hand with additional copies of your key piece
