The purpose of Taunt ("picador") is generating aggro: it attracts enemies according to its strenght. If a Vega Taunt can attract a Sirius enemy that is because it is generating a litte amount of aggro besides nobody else. As soon as other player can generate more aggro (by shooting it, per example) the enemy will switch its target. That is the reason many people only install a Standard Taunt (the lowest, found in Lyris) on their grinding tanks with the sole purpose of attracting a harvester ("colectora"). If you really want to attract an enemy when fighting in squad, then you should use a high level Taunt, but remember that it is not unlimited powered, your teammates can get the aggro again if they do more on the enemy (shooting, stunning, bombing, etc). Here come the Ancient ("arcanos") flavours: Normal, Long ("durable") and Strong ("poderoso"). Long is weaker than normal, but last more time; Strong is obviously stronger, but last less time. Ancient are a little more strong than system rares, but as I said, they are not unlimited.
