The defense symbol is a standard combat symbol and does not have any keyphrase abilities associated with them.
The Tiny symbol grants the Tiny Size keyphrase
The Giant symbol grants the Great Size and Giant Reach:2 keyphrases
The Colossal symbol grants the Great Size and Giant Reach:3 keyphrases and also grants the Colossal Stamina keyphrase
Colossal Stamina (Colossal) This character can be given a costed action even if it has two action tokens, and does not receive an action token for that action. After resolutions, deal it 1 unavoidable damage and don’t clear its action tokens this turn.
Giant Reach: X (Giant & Colossal) When this character makes a close attack, instead of choosing an adjacent character (or characters, if able) for target(s)', lines of fire drawn by this character can’t be hindered' and target character(s) within X squares and line of fire.
Great Size (Giant & Colossal) 'This character can move up or down across Elevated terrain (without using elevation change squares). This character does not stop moving when moving into terrain that is hindering for movement purposes and does not halve its speed value when beginning movement from terrain that is hindering for movement purposes. This character can move through Outdoor Blocking terrain. This character can move through squares adjacent to or occupied by opposing characters without stopping. (Still needs to break away.) This character can make range attacks while adjacent to opposing characters. (May target adjacent or non-adjacent opposing characters.)' Lines of fire drawn to or from this character are not blocked by elevated terrain or outdoor blocking terrain, and are hindered only if the line of fi re is drawn to a square of hindering terrain that includes the target.
Tiny Size (Tiny) Modify defense +1 against range attacks