Survivor Heart

Info
The Survivor Heart has the same stats as a Lesser Heart,  but it also survives 2 lethal hits. This means that when the heart would have died, it instead survives on 1 hp, and does this twice. This survival works regardless of how much damage is inflicted in one bullet, a 16 damage bullet will only take down one hit but two weaker bullets will take down two. This heart can be obtained in shops and in item rooms.

Strategies
This heart is a very interesting one to make strategies for. Prior to Demo 8.1, this heart shined in all Amorphous boss fights (except for Amorphous Prime Phase 2) because those involve very damaging bullets that this heart can tank easily. However, the big bullets now drop acid pools so you will need to be very careful to teleport or move out of acid pools as quickly as possible: the damaged heart states do not care that acid pools do minimal damage and the fast damaging of the pools will shred right through the surviving hits. This heart is mainly a Lesser Heart with more room for error, as you can swap it out when it's damaged and retain it for later rooms. For new players who are less skilled at swapping hearts, other hearts in the shop would be preferable.

Trivia

 * This heart did not work properly in earlier demos: it survived nothing
 * There was a bug in earlier demos where survivor heart and body bag hearts gave the player invincibility
 * There was another smaller bug in earlier demos where survivor heart's damage sprites did not function correctly after the first time survivor heart survived hits
 * Theoretically, this heart can take more amorphous prime big bullets before regen than any other heart without any buffs (it can technically tank three hits and still survive, jumbo: 2, tough: 1)