From the original BukkitDev page:
"You can also find this plugin on PlanetMinecraft. 
Note: This page is not managed by me but by fillpant, any issues report them to him."
This post is a copy of the BukkitDev page, no changes where made. The quote and exact post can be found HERE

Description

Soul Shards is a recreation of the Soul Shards mod. This plugin adds in 2 items to the game, Soul Shard and the Soul Cage. The Soul Shard allows you to start capturing the souls of any monster/animal, you can then get the shard better and better by killing more of the bound mob. The shard has 5 tiers each one makes it react differently when spawning entities. Stats of the souls are below. To make the shard actually spawn the mobs you would need to put the shard into the soul cage.


You can also find this plugin on PlanetMinecraft. 
Note: This page is not managed by me but by fillpant, any issues report them to him.

Recipes:

Tiers

Tier	Souls needed	Mobs per second	Spawn latency	Needs someone within 16 blocks	Other worlds	Ignore light level
1	64	2	20	☓	☓	☓
2	128	4	10	☓	☓	☓
3	256	4	5	☓	☓	☓
4	512	4	5	☓	✓	☓
5	1024	6	2	✓	✓	✓

Config

[code]#Auto update the plugin[/code]
[code]Auto-Update: true[/code]
[code]#Enable metrics for the plugin[/code]
[code]Metrics: true[/code]

[code]#Amount of kills needed for a tier[/code]
[code]Kills:[/code]
[code] Tier-1: 64[/code]
[code] Tier-2: 128[/code]
[code] Tier-3: 256[/code]
[code] Tier-4: 512[/code]
[code] Tier-5: 1024
[/code]


TODO

• Active and deactive tier 5 with redstone
  

Milestones

Download milestones: http://dev.bukkit.org/bukkit-plugins/soul-shards/milestones/downloads/