A lot of people new to the franchise will go bankrupt with extra lifes.
A new mountable Item: Permanent Chance
This Item is a Auto-use item, 3 maximum, that lasts infinite missions. It would give +1 extra life, but will make your weapon damage Slightly weaker (5% weaker). This Item costs 250 keys. IF possible, make it a gift at tier 5 or 10. That way, players would survive much more time with less keys lost.
Begineers have a lot of easy missions to try and survive with just 1 lives. and those missions are a suitable place to farm keys from. Besides I may remind of that 50% nerfed difficulty that begineers have in very early moments of their gameplay.
I don’t think that adding a new item would be good game design, especially if that nerfs your offensive capabilities and gives you only one life.
New players die a lot. One extra life isn’t enought.
I think the old life system should be re-implemented:
…Invasion missions have a tier requirement of 0. All of them. A mission with 100% difficulty effectively turns into a 60% difficulty mission at tier 1.