#include <iostream>
#include <algorithm>
#include <cstring>
#define int long long
using namespace std;
int c[200010],g[300010];
int magic(int n,int m) {
int x = n / m,y = n % m;
return (n - 1) * n / 2 - (x - 1) * x * (m - y) / 2 - x * (x + 1) * y / 2;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t;
cin >> t;
while (t--) {
int n,b,x;
cin >> n >> b >> x;
int maxn = 0;
for (int i = 1;i <= n;i++) {
cin >> c[i];
maxn = max(maxn,c[i]);
}
for (int i = 0;i <= maxn + 1;i++) {
g[i] = 0;
}
for (int i = 1;i <= n;i++) {
for (int j = 1;j <= c[i];j++) {
int t = magic(c[i],j) * b;
g[j] += t;
if (j + 1 <= c[i]) {
g[j + 1] -= t;
}
}
}
int ans = 0;
for (int i = 1;i <= maxn;i++) {
g[i] += g[i - 1];
ans = max(ans,g[i] - (i - 1) * x);
}
cout << ans << '\n';
}
return 0;
}
