Mana is generally given by lands, a particular card type, and players can usually play up to one land per turn, which is a mechanic in MtG that keeps the game more balanced, preventing you from playing a game-winning card on turn 1 if you get the right combination of lands and cards in your hand
Creature - Sphinx Color tag templates(None) Subtlety Flash Flying When this creature enters, choose up to one target creature spell or planeswalker spell
Finally, as mentioned, steal your opponent's win conditions
Unlike Gifts Ungiven, Harmless Offering allows you to actually give one of your permanents to an opponent
Its an easy and quick way to power up your Inkwell
With that, you can then use cards like Knight of the New Coalition, Xerex-Strobe Knight and the bomb Invasion of New Phyrexia to make Knight tokens and go wide