The person that makes the row match uses his value for all the color. For example if Magneto does 50 per blue and 5 per red, and Thor does 50 per red and 5 per blue and you match 4 blue and there 4 more red on the side, you get 4X50 + 4X5 = 220. It’s subject to cascade so if something else formed a match on top of that match 4 the damage for the match 4 may be reduced. Also if the match 4 forms multiple matches in that row, you get the damage for both matches even though some of the tiles will be counted twice.