There are various drawing cards for different decks.
For example : Six Samurai, you have a perfect card: Six Samurai United
I can give you some good cards for draw power, but some will be specific to each deck:
Reckless Greed.
This can be put into any deck. However, this card can be your downfall if used in the wrong way. Always set AT LEAST 2 at once.
Shard of Greed.
I wouldn't really trust this as an MST can easily wipe it out and leave you without a draw.
You have lots of others, like advance draw, allure of darkness, destiny draw, even jar of greed and legacy of yata-garasu.
If you give me a specific deck, i can give you the best possible drawing cards.