Add a Void Drain to Tinker's where you can add a filter for a liquid that will be automatically voided from the smeltery. I often end up with a small amount of blood in the smeltery from mobs blocking the desired metals. The Void Drain would automatically remove the lowest liquid if it matches the filter liquid.
A mod that allows you to enchant an oak sapling with Fortune to grow golden or Notch apples. The sapling would need to be planted on a a dirt block with either a block of gold or diamond one block below. Every full moon, there would be a small change that the tree would grow a golden or Notch apple. There would be a small chance the the apple would actually be a poison apple and insta-kill the player (configurable).
A mod that grows mobs from seed-like items. As the plant grows, it starts taking on the characteristics of its mob until the plant ripens and the mob is released. For example, killing animals would randomly drop corrupted flesh that can be planted to grow a zombie, bones grow skeletons, breaking leaf blocks randomly drop a sinister vine to grow a creeper. Passive mobs could be grown by combing carrots, barley or wheat with growth medium to yield pigs, sheep, and cows.
The mod could be used in situations where normal mob spawns are disabled but you need the resources for progression.