Warsmash is the closest thing to a "Warcraft 3 Android APK". It is an open-source mod engine built with LibGDX that can read the original game’s assets. You download the Warsmash APK from F-Droid .
Any website offering a file named "Warcraft 3 Android APK" is not providing an official Blizzard product. warcraft 3 android apk
If you own a PC at home that can run Warcraft 3, you can stream it to your Android device. Warsmash is the closest thing to a "Warcraft 3 Android APK"