Hi
As per your spec, and I have added one more condition for minutes before the off, your trigger should look like this:
back
price: back_price
amount: 2.00 (or put your backing amount)
selections: second favourite
markets: all markets
execute: once per market
market status: idle or suspended
conditions:
markets minutes before the off is less than 1.00
and second favourites back price is between 3.00 and 5.20
please test in test mode