In addition to gold and XP from the 100 habitat fights, the packs give bonuses to the corresponding attributes of a hero: 1% per pet of the respective element found.
In addition, for each pet that reaches level 100, there is a 0.5% bonus on the respective attribute. This bonus is increased to 0.75% when reaching level 150 and to 1% when reaching the maximum level of 200.
Water pets give a bonus to strength, light to dexterity, earth to intelligence, shadow to constitution and fire to luck.