Guild Wars 2

Mesmer swiftness from focus does not add up with swiftness from other sources and is not replace an older swiftness buff even if the current swiftness has a shorter duration left.

So often reported …

As DesertRose said, if it’d stack swiftness each time, you could abuse it by running through it 4 times. It did behave like this in the beta and got “patched”.

There are multiple suggestions to fix it without making it too strong, but ANet sees this issue as a minor one (if actually).

1. Only if the current, total swiftness duration is lower than TCs 12s (+boon dur) set it to its duration. Meaning, if you run through it with 1s swiftness left, it becomes 12s; if you have 13s, it stays 13s.
2. Like Guardians SoS, add at least 1s swiftness when you already have swiftness (bad fix)
3. Instead of giving 1 stack of 12s, it could give 5 stacks of 2.4s each. Since duration stacking boons are limited to 5 stacks, it’d wouldn’t fully stack with other durations, but will add a decent amount.
4. Check if any of the current swiftness sources is the TCs mesmer. If not, add swiftness.