Itd be nearly impossible to know even half of them, so having a good and reliable database is fundamental
(It's an artifact with "2, T, Sacrifice this artifact: You gain 3 life.") If an instant or sorcery spell has an adamant ability, you perform the spell's instructions in order
If you do, that land becomes a 0/0 Elemental creature with haste thats still a land
Alternatively, if you go the group hug route, you can help buff another players creature, though the flying unfortunately wont last long enough to matter
If a card is neither and serves no fundamental purpose, then you dont need it
In Modern and Legacy, there are plenty of Legendary spells that are super important to the gameplans of lots of different decks