Gaius Marius is a Caesar prestige hero and requires 20,000 prestige to unlock.
Unit Type - Lancers: High Critical Strike Rate. Gambit - Spearhead: Attack a column (player perspective = left to right) of enemies for gambit damage.
Gaius Marius is a superior version of Alfred and Attila. His gambit attack, Spearhead, is the same as Aflred's which which deals 100% of your Gambit Attack value, whereas Attila's Impudent Advance deals about ~80% and then deals additional damage through the Poison effect, overall averaging out to about equal damage to Spearhead.
He has great Bravery and moderately high Tactics considering how easy it is to get him. Caesar players should be using him as their heavy hitter for a while.
Gaius gains 30 units per level