There's a reason the cards got master of death written in it.
It works well if you have a darkness deck, though any other deck with a decent amount of darkness cards would work too.
Strategies and game play:
I generally keep two in the deck, because of its high cost if you get one early on its better to use it for mana and youll still have another one lying in the deck.
Personally i wouldnt wait for a ballom, id try to finish the game by the time you reach around 5-6 mana otherwise by the time you reach 8 mana your opponent would have the same amount of mana too.
Hence ballom is basically a bit of a gamble but once you summon it its basically a sure shot win.
Combos with other cards:
if you have a gregoria ballom becomes a blocker with +2000, theres also chaotic sky terror which gives all demon commands double breaker +2000.
Ways to counteract it:
Terror pit/ hopeless vortex works like a charm, any slayer alcadias or uberdragon bajula assuming you manage to summon them after ballom.
power 12000, the only creatures capable of equalling that power are alcadias, uberdragon bajula, super necro dragon abzodolba (only if you have a huge stack in the graveyard). All creatures other than darkness are destroyed and its a double breaker.
Huge cost, hard to use in decks which dont have a decent amount of darkness creatures
english and japanese