// Problem: No.2793 Mancala Master
// Group: yukicoder
// URL: https://yukicoder.me/problems/no/2793
// Memory Limit: 512 MB
// Time Limit: 2000 ms
// Author: lingfunny
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
using namespace std;

using LL = long long;

template<class T>
constexpr T power(T a, LL b) {
    T res {1};
    for (; b; b /= 2, a *= a) {
        if (b % 2) {
            res *= a;
        }
    }
    return res;
}

constexpr LL mul(LL a, LL b, LL p) {
    LL res = a * b - LL(1.L * a * b / p) * p;
    res %= p;
    if (res < 0) {
        res += p;
    }
    return res;
}

template<LL P>
struct MInt {
    LL x;
    constexpr MInt() : x {0} {}
    constexpr MInt(LL x) : x {norm(x % getMod())} {}
    
    static LL Mod;
    constexpr static LL getMod() {
        if (P > 0) {
            return P;
        } else {
            return Mod;
        }
    }
    constexpr static void setMod(LL Mod_) {
        Mod = Mod_;
    }
    constexpr LL norm(LL x) const {
        if (x < 0) {
            x += getMod();
        }
        if (x >= getMod()) {
            x -= getMod();
        }
        return x;
    }
    constexpr LL val() const {
        return x;
    }
    constexpr MInt operator-() const {
        MInt res;
        res.x = norm(getMod() - x);
        return res;
    }
    constexpr MInt inv() const {
        return power(*this, getMod() - 2);
    }
    constexpr MInt &operator*=(MInt rhs) & {
        if (getMod() < (1ULL << 31)) {
            x = x * rhs.x % int(getMod());
        } else {
            x = mul(x, rhs.x, getMod());
        }
        return *this;
    }
    constexpr MInt &operator+=(MInt rhs) & {
        x = norm(x + rhs.x);
        return *this;
    }
    constexpr MInt &operator-=(MInt rhs) & {
        x = norm(x - rhs.x);
        return *this;
    }
    constexpr MInt &operator/=(MInt rhs) & {
        return *this *= rhs.inv();
    }
    friend constexpr MInt operator*(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res *= rhs;
        return res;
    }
    friend constexpr MInt operator+(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res += rhs;
        return res;
    }
    friend constexpr MInt operator-(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res -= rhs;
        return res;
    }
    friend constexpr MInt operator/(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res /= rhs;
        return res;
    }
    friend constexpr std::istream &operator>>(std::istream &is, MInt &a) {
        LL v;
        is >> v;
        a = MInt(v);
        return is;
    }
    friend constexpr std::ostream &operator<<(std::ostream &os, const MInt &a) {
        return os << a.val();
    }
    friend constexpr bool operator==(MInt lhs, MInt rhs) {
        return lhs.val() == rhs.val();
    }
    friend constexpr bool operator!=(MInt lhs, MInt rhs) {
        return lhs.val() != rhs.val();
    }
    friend constexpr bool operator<(MInt lhs, MInt rhs) {
        return lhs.val() < rhs.val();
    }
};

template<>
LL MInt<0>::Mod = 998244353;

constexpr int P = 998244353;
using Z = MInt<P>;

const int mxn = 2e5 + 10;

int a[mxn];

void solve() {
	int n, k;
	Z res = 1;
	cin >> n >> k;
	{
		Z cur = 1;
		for (int i = 1; i <= n; ++i) {
			cin >> a[i];
			cur *= k;
			res *= cur - 1;
		}
	}
	{
		LL tot = 0;
		for (int i = 1; i <= n; ++i)
			tot += 1ll * i * (a[i] - 1);
		res *= power(Z(k), tot);
	}
	cout << res << '\n';
}

int main() {
	int TestCase;
	for (scanf("%d", &TestCase); TestCase--;) solve();
	return 0;
}

// f(x + y) - f(x + y - 1) = f(x)f(y)

// k^{M-c}(k-1)^c