May Fusion

You're misunderstanding what he was saying. Cillian as a champ is decent, but as a fusion was pretty bad. He's good in Arena, but he generally won't push you further in Arena. You can get to and stay in Gold 4 with pretty basic teams (like HK, Spirithost, Warmaiden, starter) so long as you understand matchups and have solid gear. He's good in FW, but that is not going to be a focus for most players and he alone won't push you much farther along there. He generally won't push you farther into dungeons, and is useless for CB. Does all that make him a bad champion? No. So is he worth all the effort needed to get from the fusion? Not really. If you're still progressing through the game the fusion will be more difficult and the reward is...slightly better gylphs every once in a while and maybe a bump in Arena. Meanwhile if you're done with progression and can do the fusion pretty easily, your reward is...slightly better glyphs every once in a while and maybe the ability to sit more comfortably in Gold 4. Plus he wants a lot of Legendary books to get to his maximum potential.

Also Hegemon is better due to his passive. Guaranteeing the ability to go first and potentially cripple the entire enemy team is massive, plus being Void means no weak hits that can prevent the debuff from applying. Cillian can do similar things with enough speed, but it's not guaranteed (and directly loses to Hegemon) and you have to cut back on other stats to maximize his speed whereas Hegemon can run something like a Savage set.

/r/RaidShadowLegends Thread Parent