Guardian Angel's Elixir
GA has fallen out of use for a little while, since it's hard to justify using a whole item slot for a few stats and a hit/miss passive effect.
It would be a elixir that you purchase, and it would give you GA's passive effect. The cooldown would be shared with the actual GA item, so you can't stack the effect.
This would offer a strategic niche for an upcoming team fight for 500 gold, that would be different to the other elixirs.