Slows enemies. There is an unused upgrade that makes tar 150 coin cheaper. The bug with fire tar is that the effect stacks and give more that 30% bonus damage depending on the trap. Floor scorchers do 60%, fire lasers are around 80%, flame bracer LMB is 39%. Robot Entertainment indicated they would not be fixing this since it's small and would technically be a nerf.
| Increase Slow [+2.5% slow, 42.5%] - 4💀 | Slow enemies for 600 seconds to unlock |
| Increase Slow More [+2.5% slow, 45%] - 7💀 | Enemies Remain Slowed for a Brief Time
[+1 second, 1] - 7💀 |
| Increase Slow Even More [+5% slow, 50%] - 9💀 | Enemies Take Increased Fire Damage on Tar
[+30% (although bugged)] - 8💀 |