Speedster is a "Soldier" unit, his main role is damage the enemy nexus.
Passive: Dancing In The Rain
This unit moves so fast it can dodge bullets
Active: Dance with Me
Increase attack units dodge rate for a short period
Tactics:
passive - dodging capabilities means this unit can survive longer under fire, in addition if the unit dodge an AOE spell - the AOE effect is voided.
active - "Dance with Me" benefit all of the units on the field granting them some dodge rate.
this skill can go really well with "Nukers" skill as it can help getting your units closer and the "Nuker" skill will allow them attacking from range.