Paladin Class

If Paladin Class is level 3 and you attack with exactly one creature, it won't get a power and toughness bonus, but it will get double strike.

Each Class has five abilities. The three in the major sections of its text box are class abilities. Class abilities can be static, activated, or triggered abilities. The other two are level abilities, one activated ability to advance the Class to level 2 and another to advance the Class to level 3.

Gaining a level won't remove abilities that a Class had at a previous level.

You can't activate the first level ability of a Class unless that Class is level 1. Similarly, you can't activate the second level ability of a Class unless that Class is level 2.

Gaining a level is a normal activated ability. It uses the stack and can be responded to.