In League of Legends, there are many items that may be overlooked by players, but which can be very effective in certain situations. Here are some examples of items that can be underestimated by players:
Zhonya's Hourglass: This item is often overlooked by AD players, but is extremely useful for AP champions who need protection against enemies with a lot of physical damage. The active Zhonya's Hourglass allows you to be invulnerable for a few seconds, which can be very useful in teamfights.
Morellonomicon: This item is often overlooked by players who are not playing support or AP positions, but it is a powerful item that can help reduce enemy healing. Morellonomicon is a great choice against champions with healing or regeneration, such as Swain or Soraka.
Locket of the Iron Solari: This item is often overlooked by support players, but it is a great defensive item that can help protect your team. The Locket of the Iron Solari asset grants an area protection shield, which can be very useful in teamfights.
Mikael's Crucible: This item is often overlooked by support players, but can be extremely useful in helping to protect your teammates from enemy group control abilities. Mikael's Crucible asset removes group control from an ally, which can be the difference between winning or losing a team fight.
Mejai's Soulstealer: This item is often overlooked by players who are not playing in AP positions, but it can be extremely effective in games where you are doing well. Mejai's Soulstealer grants AP increase for each kill or assist, becoming increasingly powerful as you continue to win.
In general, it is important to remember that each item has its uses and can be effective in certain situations. It is always important to understand how each item works and how they can help your team achieve victory.