Please help me figure out the meaning of the phrase "buff your units" in the following sentence (not available online):
Planeswalkers are among the most powerful beings in this game and thanks to their magical abilities, they’ll buff your units and add the critical edge that’s essential for your victory.
The quoted sentence is from the description of the game Magic: ManaStrike. Here is a brief description of the game from a different source:
Not only does ManaStrike use MtG characters, but it also uses the cards. This is perhaps the most interesting thing about the mobile title, at least to anyone who's a fan of MtG. Seeing how the creatures and spells I love are translated into a different style is fascinating.
Take Giant Growth, for example, a card that gives a creature extra strength and defense in the card game. In ManaStrike, it provides a creature with additional health instead of strength.
Thank you for your time.