黙示録のハイドラ

黙示録のハイドラは、＋１/＋１カウンターがＸ個置かれた状態で戦場に出る。Ｘが５以上であるなら、これは追加の＋１/＋１カウンターがＸ個置かれた状態で戦場に出る。
{1}{R}, 黙示録のハイドラの上から＋１/＋１カウンターを１個取り除く：クリーチャー１体かプレイヤー１人を対象とする。黙示録のハイドラはそれに１点のダメージを与える。

末日多头龙

末日多头龙进战场时上面有X个+1/+1指示物。如果X等于或大于5，则它进战场时上面额外有X个+1/+1指示物。
{1}{R}，从末日多头龙上移去一个+1/+1指示物：末日多头龙对目标生物或牌手造成1点伤害。

Apocalypse Hydra

This creature enters with X +1/+1 counters on it. If X is 5 or more, it enters with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Battlebond

Apocalypse Hydra enters the battlefield with X +1/+1 counters on it. If X is 5 or more, it enters the battlefield with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from Apocalypse Hydra: Apocalypse Hydra deals 1 damage to any target.

Modern Masters 2015

Apocalypse Hydra enters the battlefield with X +1/+1 counters on it. If X is 5 or more, it enters the battlefield with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from Apocalypse Hydra: Apocalypse Hydra deals 1 damage to target creature or player.

Conflux

Apocalypse Hydra comes into play with X +1/+1 counters on it. If X is 5 or more, it comes into play with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from Apocalypse Hydra: Apocalypse Hydra deals 1 damage to target creature or player.

For example, if X is 4, Apocalypse Hydra enters with four +1/+1 counters on it, but if X is 5, it enters with ten +1/+1 counters on it.

The first ability checks the number you chose for X, not the amount of mana you actually spent.