How can i report a player??

In my game, i have a player destroying easy 3 countries, he made a very big army so fast in 1 day and i tried to def myself vs 10 cars, i send an army like 15 troops, i defend the zone, i saw if i def, i had more dmg than him if he attacks i calculated he cant catch the zone before me, even if he uses quick march, so, a victory for me, but no, he win but not only that, cars are at 75% health, what???

My allie see strange things with that player too, we thought he just is using gold, maybe too much, i know in this game players can do that and no problems with that, but now i suspect, or he is using too much gold or he is just hacking, cause its not normal the gold he put in that game in the case this is happening

Maybe someone can say, well, he is just a better player, but is normal in 1 day having an army can destroy easy 3 countries?? At least 2 of them are active, mine and my allie countrie and last thing, the strangest, my battle vs that 10 cars, for attack points, i will win that but no, he win, but thats not all, his cars are at 75% of hp, thats a very big nonsense, just 2 things, gold (with this im aware i cant do nothing, is legal in this game doing that) or he is hacking in someway, cause ok, if he is using gold, he is using a lot, too much, thats is very suspicious, i dont think he is just using money to win