From Melvor Idle
This page is up to date (v1.2.2).
Pet ID: melvorF:Mark
Source: Summoning
Drop Chance: See: Acquiring Pets
Effect: +10% Chance to preserve Summoning Charges
Part of 100% Completion: Yes

Mark is a pet acquired differently from other skill pets, and is unlocked when the player reaches the mark level of 4 in each of the base game Summoning marks.