Akkord des Rufes

Einberufen (Deine Kreaturen können dir helfen, diesen Zauberspruch zu wirken. Mit jeder Kreatur, die du tappst, während du diesen Zauberspruch wirkst, bezahlst du für {1} oder ein Mana der Farbe jener Kreatur.)
Durchsuche deine Bibliothek nach einer Kreaturenkarte mit umgewandelten Manakosten von X oder weniger und bringe sie ins Spiel. Mische danach deine Bibliothek.

Corde d'adjuration

Convocation (Vos créatures peuvent aider à lancer ce sort. Chaque créature que vous engagez en lançant ce sort paie {1} ou un mana de la couleur de cette créature.)
Cherchez dans votre bibliothèque une carte de créature avec un coût converti de mana inférieur ou égal à X et mettez-la sur le champ de bataille. Mélangez ensuite votre bibliothèque.

召喚の調べ

召集（あなたのクリーチャーが、この呪文を唱える助けとなる。この呪文を唱える段階であなたがタップした各クリーチャーは、{1}かそのクリーチャーの色のマナ１点を支払う。）
あなたのライブラリーから、点数で見たマナ・コストがＸ以下のクリーチャー・カード１枚を探し、戦場に出す。その後、あなたのライブラリーを切り直す。

和声召集

召集（此咒语能用你的生物来协助施放。你于施放此咒语时每横置一个生物，就能为此咒语支付{1}或一点该生物颜色之法术力。）
从你的牌库中搜寻一张总法术力费用等于或小于X的生物牌，并将之放进战场。然后将你的牌库洗牌。

Chord of Calling

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

You never really know when a new Miku fan might make an appearance.

Secret Lair Drop

Ravnica Remastered

Convoke
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Explorer Anthology 3

If a card in a player's library has {X} in its mana cost, X is considered to be 0.

Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.

If a creature you control has a mana ability with {T} in the cost, activating that ability while casting a spell with convoke will result in the creature being tapped before you pay the spell's costs. You won't be able to tap it again for convoke. Similarly, if you sacrifice a creature to activate a mana ability while casting a spell with convoke, that creature won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for convoke.

Tapping a multicolored creature using convoke will pay for {1} or one mana of your choice of any of that creature's colors.

Tapping an untapped creature that's attacking or blocking to convoke a spell won't cause that creature to stop attacking or blocking.

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.

When using convoke to cast a spell with {X} in its mana cost, first choose the value for X. That choice, plus any cost increases or decreases, will determine the spell's total cost. Then you can tap creatures you control to help pay that cost. For example, if you cast Chord of Calling (a spell with convoke and mana cost {X}{G}{G}{G}) and choose X to be 3, the total cost is {3}{G}{G}{G}. If you tap two green creatures and two red creatures, you'll have to pay {1}{G}.

You can tap any untapped creature you control to convoke a spell, even one you haven't controlled continuously since the beginning of your most recent turn.