The red number.
For example...If someone's power (Blue number) is 3 and their damage (red number) is 8, basically it means 'If this card wins, then it will take 8 damage from the opponent's life'.
This is also facotred into by abilities and bonuses that may reduce or add to it, as well as fury (Using 3 pills to give you 2 damage)
The red thing. Called the damage. I will try to lay it out
Your card has a POWER and a DAMAGE
POWER = ATTACK POWER times X amount of pills.
If a character has 6 POWER they start the round REGARDLESS with 6 ATTACK POWER (1 pill is auto given to you so you don't go in w/o any attack power.
Every pill you use would attack another 6 Attack power. So if you *USE* 4 pillz, you would have 4x6 24 +6 (your original power) it would look like you are using 5 pillz but only 4 pillz would be subtracted. So you would have a total of 30 ATTACK POWER.
Now if you had a character that did 5 damage and you WON you would do 5 damage to your opponent. Your character would be known as a 6/5 character.
Things that alter Attack power: Bonus, Ability, Hugo (leader).
Things that alter Character power: Bonus, Ability, Ambre (leader).
Things that alter Damage: Bonus, Ability, Timbre (leader).
That is about it.
If you aren't playing in a no random room that would be the reason. In all rooms except the non random rooms there is the random factor. You won't win everytime you have a higher attack in those rooms. Only in No Random rooms do you win everytime you have higher attack.
If you are losing rounds randomly, then you are playing in a room that allows random. Attack power just increases your chance to win but if it is not double then you still have a CHANCE to lose.
If you play in a room that is no random (my personal preference) and you have even 1 point more of Attack power then you will always win.