How do you kill a summoned phoenix?

That's all well and good in a game, but what about in a duel on the anniversary, if someone summons it, then how?

In a duel, Fen is summoned with: Dyraell, Jaleeb. And against these heroes, Haven doesn't work. Against Dyraell, they usually take Ravenna – she deals with Fen using cold, but it should be noted that Dyraell doesn't summon Fen in 75% of cases because he doesn't have enough mana.
Fen from Jaleeb is much more serious and dangerous. Against Jaleeb, I usually play Iris (and everyone knows what she has), so there are no problems with Fen there either.