歩行バリスタ
アーティファクト・クリーチャー — 構築物
アサルトロン・インベーダーは＋１/＋１カウンターＸ個が置かれた状態で戦場に出る。
：アサルトロン・インベーダーの上に＋１/＋１カウンター１個を置く。
アサルトロン・インベーダーの上から＋１/＋１カウンター１個を取り除く：１つを対象とする。これはそれに１点のダメージを与える。
イラスト：
Fallout#352レア日本語適正
裁定
A casting cost of means that you pay twice X. If you want X to be 3, you pay 
to cast Walking Ballista.
If Walking Ballista has been dealt damage or had its toughness reduced by an effect, this limits how many times you'll be able to remove +1/+1 counters from it in a single turn. For example, if it has three +1/+1 counters on it and has been dealt 1 damage this turn, it will be destroyed immediately after you activate the ability a second time and you won't be able to activate it a third time.
A casting cost of means that you pay twice X. If you want X to be 3, you pay to cast Walking Ballista.
If Walking Ballista has been dealt damage or had its toughness reduced by an effect, this limits how many times you'll be able to remove +1/+1 counters from it in a single turn. For example, if it has three +1/+1 counters on it and has been dealt 1 damage this turn, it will be destroyed immediately after you activate the ability a second time and you won't be able to activate it a third time.