自行弩炮

Text:

自行弩炮进战场时上面有X个+1/+1指示物。
：在自行弩炮上放置一个+1/+1指示物。
从自行弩炮上移去一个+1/+1指示物：它对目标生物或牌手造成1点伤害。

Rulings:

• 8/7/2020 A casting cost of <img src="/Handlers/Image.ashx?size=small&amp;name=X&amp;type=symbol" alt="Variable Colorless" align="absbottom" /><img src="/Handlers/Image.ashx?size=small&amp;name=X&amp;type=symbol" alt="Variable Colorless" align="absbottom" /> means that you pay twice X. If you want X to be 3, you pay <img src="/Handlers/Image.ashx?size=small&amp;name=6&amp;type=symbol" alt="6" align="absbottom" /> to cast Walking Ballista.
• 8/7/2020 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.