This achievement requires buying and upgrading five skills from Opher in Wellspring Glades.
The base skills cost 400 spirit light each and the upgrades cost 1200 spirit light each (on Normal- these prices are halved on Easy and doubled on Hard).
The skills are Sentry, Spirit Star, Blaze, Spirit Smash, and Spike.
I found the best farming spot (here's a GIF
) to be just outside the right exit of Wellspring Glades. Use Spirit Smash on the purple projectile enemy which respawns immediately and drops an increasing amount of Spirit Light (it built up over time for me) when you use the Bounty and Light Harvest shards.