Hero collecting RPG Calibria: Crystal Guardians is going strong two months on from its launch on iOS and Android devices, and for newcomers to the fold, it’s helpful to understand how the game’s character tiers work before diving in head-first.

Each hero is assigned a star level of between one and six, but what does that mean? Well, one star or two-star heroes, such as Wood Elementals and Imps, are basically the "enhance food" for higher star level heroes, although they have their uses in the game’s early battles.

There are many useful assist type three-star heroes, while four-star heroes are the ones with lofty potential. You can train them up to lead your team and eventually propel them to the ranks of five and six stars.

Few beginners are lucky enough to summon a five-star hero and six-star characters cannot be summoned at all, although five-star heroes can be evolved to this rank.

Published by Mars Games, Calibria: Crystal Guardians is a 3D role-playing game that combines hero collecting with combat and strategy elements. It takes place against on the fantasy island of Calibria, where the forces of good and evil are at war over a sacred crystal.

Players must assemble a team of heroes from a huge roster of 200 characters, spanning five different factions and bringing a plethora of unique skills to the battlefield.

You can upgrade and customise your dream team and have them run the gauntlet across several game modes: Spire, Battles Arena, Dungeons and the Campaign. Outside of these modes, players can group together in guilds and go head-to-head on the leader boards.

Calibria: Crystal Guardians is available to download for free from the App Store and Google Play.