For instance: Green/x Manabase: 6 Forest 1 Mountain 1 Plains This might be a manabase found in a Green Devotion deck that wants to reliably have as much green as possible but supports both red and white splashes off of fetchlands, Mana Confluence, and Sylvan Caryatid
Adding the hand created a lot of value and meant you wouldn't have to lose a permanent on the battlefield
There are a ton of legendary creatures from this era that you could build decks around, though there are a lot of clunkers too
This discounting mechanic scales rapidly, allowing big-impact plays much earlier than opponents expect, and it pairs well with self-mill strategies that keep the graveyard stocked
Fetchlands make that price much, much less
It wont do much if cast on the cheap, but this is a potential draw five that copies the best thing in play once you get to seven-plus mana