Venerable Lord Kroak has a more powerful version of telepathy than other Slann Mage-Priests. His powerful spirit is capable of entering the bodies of those who open themselves up to him and can use them as mediums through which he can cast spells.
Kroak can use Slann Mage-Priest telepathy as normal. If he wishes, however, he may instead choose to cast the spell through a friendly wizard, resolving all the effects as if Lord Kroak himself was in the position of the medium. Choose any friendly Skink Priest or Slann Mage-Priest on the table to project his spirit into. Lord Kroak cannot use the host's spells, only his own. He may project himself into any number of models in the one Magic phase.
If he suffers a Miscast when casting through a medium, Lord Kroak's spirit is blasted from its host, and he cannot cast any more spells through that model that Magic phase. The spell automatically fails, though no roll on the Miscast table is taken.
If the spirit of Lord Kroak used a Skink Priest to cast spells in the Magic phase, then at the end of that Magic phase the player must take a Leadership test for each Skink that Kroak cast spells through. If this is failed, then the Skink Priest swoons under the power and cannot move in his next Movement phase. If it is engaged in combat, it cannot fight and will be hit automatically. This lasts until the start of the next Lizardmen Magic phase.