Card effect
On Deploy: this hero and the Arcomia Core +2 levels.
Skill

Dazzling Revolver
Marco Polo draws his Dazzling Revolver and fires 8 bullets in his current direction, each dealing 25+15% physical attack as physical damage. After defeating an enemy with the skill, his next cast fires 8 extra bullets.
Upgrades
10lv
Bullet damage increased to 40+25% physical attack
40lv
Number of bullets increased to 16
100lv
Enemies hit by Marco Polo's bullets are permanently marked; allies attacking marked enemies gain 50% attack speed
Awakened card

Marco Polo
On Deploy
This hero and the Arcomia Core +4 levels.
Sunset Sea
On Deploy: this hero and the Arcomia Core +4 levels.
Cards that grant this

Rise
Gain 1 Marco Polo and 1 Shouyue. When fighting together, they gain 3 temporary levels. On a win, they keep up to 20 of the temporary levels gained.
How to obtain
Source: obtained from the shop, auctions and other channels