Basics | Boosts | Enchant | Immortals | Items
Boosts are temporary effects that last for 250 kills on all members of your party. Generally they increase resource gain in some way, and you cannot apply more than one of each type to your character.
Kills made during Versus mode do not count towards your 250, as the resources gained here cannot be earned while playing versus mode. This lets you continue to play Versus mode without wasting your Boost.
You can apply more than one of a particular category, provided that the bonus amount differs. The amounts stack additively. This lets you create significantly powerful boosts if you are looking to supercharge your character.
You have purchased a medium (100%) and major (200%) pure source boost. This gives you a total of 100 + 200 = 300% pure source boost. You kill a monster normally worth 100 pure source. Instead, you earn 100 * (1 + 300/100) = 100 * 4 = 400 pure source.