Rules FAQ
There is no rounding involved here. For each increment of 5 strength, the Red Viper gains 1 power. So winning by 4 strength nets 0 power, 9 strength nets 1 power, 14 strength nets 2 power, etc.
Lord.
Reaction: After you win a challenge in which The Red Viper is participating as an attacker, he gains 1 power for every 5 STR by which you won the challenge.
Link: Decklists
Rules FAQ
There is no rounding involved here. For each increment of 5 strength, the Red Viper gains 1 power. So winning by 4 strength nets 0 power, 9 strength nets 1 power, 14 strength nets 2 power, etc.