Archers have no real strength in terms of countering units, they just deal high damage and are very fragile. They just do well against everything with their long range and strong attacks.

Archers are hard countered by Area of effect damage such as hero abilities or spiders. Calvary units or other flanking units such as goblin raiders do well against archers.

Research upgrades unlock at academy level 1 for the archer.

Tier 1: Fitness Training – Flat health increase per level of research, leads to silver archers.
Tier 2: Combat Training – Flat damage increase per level of research leads to Arm Strength, which increases the range of Silver and Gold Archers by 2
Tier 3: Advanced Agility Training – Increase the attack speed of archers by +%, this leads to Advanced Lethality, which increases archers chance to crit by 10%
Tier 4: Basic Fitness Training – Bonus +% health, leads to Gold Archers.
Tier 5: Convalescence – reduced heal time, leads to reduced heal time for garrison troops by 40%
Tier 6: Advanced Fitness Training – bonus +% health, leads to bloodlust, which provides a 30% damage boost during morale.
Tier 7: Garrison Training – bonus health and damage while on garrison duty. Leads to Grassland bonus (+20% health and damage while fighting on grassland battlefields)
Tier 8: Training Discipline: reduce cost to produce archers, this leads into research which reduces crystal cost to produce archers by 20%
Tier 9: Elite Combat Training: – increases attack rating by +%, leads to +20% damage research.
Tier 10: Advanced Convalescence – more reduced healing time, leads to even more reduced healing time for garrison troops.
Tier 11: Elite Agility Training – increase attack speed of archers by +%, leads to Elite Lethality, which increases archers critical strike chance by another 20% for a total of 30%
Tier 12:Elite Combat Training – more bonus +% health, leads to Regroup which increases the size of archer troops from 24 to 27.