Cards with no answer just aren't fun.
Yep, you clearly have this MtG way of looking at Elements.
There are many "answers" to immortal creatures.
- Kill the opponent faster than he kills you
- Shields
- Healing
- Sundial
etc.
Just because you cannot kill immortal characters doesn't mean there are no "answers" to those cards. Winner is not the player who has more creatures, winner is the player who kills the other player.
No, I don't "clearly" have a M:TG way of looking at anything. M:TG is one of dozens of card based games I played before even beginning to try any of the now many online "card" games so I have no idea why you have fixated on it, other than it is probably the best known\most popular.
None of your "answers" to Immortal creatures are actual answers, they are work arounds.
If for example, "kill the opponent faster than he kills you" was an acceptable design element, then we could simply create solitaire decks with no interaction and simply clock out who kills on the fastest round.
It can be done, but we'd all soon get bored of that.
If we're giving each other advice on how to deal with an Immortal deck, then your answer is perfect, but if we're discussing the design of the game, your answer is sorely lacking.
Perhaps you are the minority though that enjoys a dynamic that has no counter-measure, and if so, we'll have to agree to disagree.