If Sett dies and is saved by the legend ability (which spends Sett's buff), does orange Sett get the +4 Might from its ability?

Ruling: No. Orange Sett's ability is an activated ability that requires you to actively declare and pay the cost to gain the +4 Might. It is not a triggered ability that automatically happens when the buff is spent.

Nuances:

• Triggered abilities use "When" or "At" in their text and happen automatically when their condition is met
• Activated abilities use ":" in their text and work like spells - you must actively pay for them and can only play them at the proper timing
• The legend ability spending Sett's buff does not automatically trigger orange Sett's ability because it is an activated ability, not a triggered one