Reference

Slime

Slime The ability: Sacrifice, Gives 100 Skill EXP when sacrificed.

Slimes can’t be used in battle. Instead, they’re used to increase your Heroes’ skill levels.
Hero Altar – Consume any Sacrifice

Sacrifice

Claim

Hire more powerful Heroes at the Hero Altar!
Switch your Heroes Altar to Item Mode to store hired cards and essences in the Warehouse.
You can hire Heroes by spending Shards, Gems, or Honor.

Hire Hiring Cost Chances *
Hire a Hero using HB. 500 Star 65%
Hire with Shards 5 Shards 100 %

* -Chances are approximate.