What each Rotten Blood taint gives you — and what it costs. Verified numbers from the community wiki; the few CipSoft never published are marked as such.
Regular taints
One taint per DIFFERENT child of Bakragore killed — repeating the same boss never adds one. Effects always stack in the same fixed order.
+0%
Second loot roll chance
Official: +7.8% per taint, additive; the final taint counts as one more step (max 39%).
Monster XP in the Rotten Blood areas also rises with every regular taint.no official figure
On hunts, regular monsters never drop the bag — they drop Tainted and Darklight Hearts: anyone contributing to the kill with at least one taint of their OWN can receive them (via Reward Container), and the chance rises with each taint.no official figure
The Bag You Covet itself only drops from the bosses (the four children and Bakragore) — more taints raise the chance; Crimson Offerings are the alternative route.no official figure
Bakragore also has a first-kill chance: until your first bag drops, the chance is considerably higher; after that it accumulates with every bagless kill and resets once one drops (CipSoft-confirmed, % never published).
Verified tip: the bags are an exception to the Bosstiary equipment loot bonus — Rotten Blood bosses in your boss slot raise the bag chance too.
Boss essences (Murcion, Ichgahal, Chagorz, Vemiath) can only be looted with the final taint — the more regular taints on top, the higher the chance. In boss rooms the WHOLE party needs the final taint for it to take effect.
Position swapneeds taint 1
Melee monsters have a 6% chance to swap positions with a player — telegraphed 2 seconds ahead on the target's tile.
Bloodjawsneeds taint 2
6.25% chance a Bloodjaw rises from a slain monster's corpse; boss fights spawn extra Elder Bloodjaws (up to 5 with the final taint).
Root + extra elementneeds taint 3
Creatures may root you and attack with a fourth element depending on the zone: Death (Jaded Roots) · Earth (Putrefactory) · Energy (Gloom Pillars) · Fire (Darklight Core).
Damage takenneeds taint 4
You receive 14% increased damage from ALL sources inside Rotten Blood.
Source: Bakragore's Taints as documented by the community on TibiaWiki (cross-checked with the Rotten Blood Quest page). The second-loot-roll series and the final taint's +4.5% XP are documented figures; the per-taint XP bonus and the Hearts / Bag You Covet chances were never published by CipSoft — marked accordingly.