Sonnenheim-Getreuer

Erstschlag (Diese Kreatur fügt Kampfschaden vor Kreaturen ohne Erstschlag zu.)
Mentor (Immer wenn diese Kreatur angreift, lege eine +1/+1-Marke auf eine angreifende Kreatur deiner Wahl, deren Stärke niedriger ist.)

"Antes de que yo te permita blandir una de estas, ¡veamos si puedes esquivarla!".

Valiente de Casa Solar

Daña primero. (Esta criatura hace daño de combate antes que las criaturas sin la habilidad de dañar primero.)
Mentor. (Siempre que esta criatura ataque, pon un contador +1/+1 sobre la criatura atacante objetivo con menor fuerza.)

« Avant de vous laisser manier un de ces cure-dents, voyons voir comment vous en esquivez un ! »

Vaillant de Solcastel

Initiative (Cette créature inflige des blessures de combat avant les créatures sans l'initiative.)
Mentor (À chaque fois que cette créature attaque, mettez un marqueur +1/+1 sur une créature attaquante ciblée de force inférieure.)

"Prima che ti lasci brandire una di queste, vediamo come te la cavi a schivarla!"

Temerario di Sol-Dimora

Attacco improvviso (Questa creatura infligge danno da combattimento prima delle creature senza attacco improvviso.)
Mentore (Ogniqualvolta questa creatura attacca, metti un segnalino +1/+1 su una creatura attaccante bersaglio con forza inferiore.)

「お前にこれを持たせる前に、躱せるかどうか試させてもらう！」

サンホームの重鎮

先制攻撃（このクリーチャーは先制攻撃を持たないクリーチャーよりも先に戦闘ダメージを与える。）
教導（このクリーチャーが攻撃するたび、パワーがこれよりも小さい攻撃クリーチャー１体を対象とする。それの上に＋１/＋１カウンター１個を置く。）

Sunhome Stalwart

First strike (This creature deals combat damage before creatures without first strike.)
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Foundations Jumpstart

Ravnica: Clue Edition

First strike
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)

Ravnica Remastered

Guilds of Ravnica

If the creature with mentor leaves the battlefield with mentor on the stack, use its power as that creature last existed on the battlefield to determine whether the target creature has less power.

If the target creature's power is no longer less than the attacking creature's power as the ability resolves, mentor doesn't add a +1/+1 counter. For example, if two 3/3 creatures with mentor attack and both mentor triggers target the same 2/2 creature, the first to resolve puts a +1/+1 counter on it and the second does nothing.

Mentor compares the power of the creature with mentor with that of the target creature at two different times: once as the triggered ability is put onto the stack, and once as the triggered ability resolves. If you wish to raise a creature's power so its mentor ability can target a bigger creature, the last chance you have to do so is during the beginning of combat step.