Marker

A marker is used to represent anything which isn't represented by a card.

• Tokens
• Emblems
• Counters
  • Energy Reserve
  • Experience
  • Poison Counter

Other

Some other mechanics are tied marker:

• Adventure — On an Adventure
• Ascend — City's Blessing
• Monarch — The Monarch
• Monstrosity — Monstrous
• Renown — Renowned

The Grand Melee variant places great emphasis on turn markers.

From the glossary of the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

Turn Markers

Markers used to keep track of which players are taking turns in a Grand Melee game. See rule 807.4.