Lil Portal 
Effects
- Summons a portal familiar that launches itself in the direction Isaac shoots to deal contact damage to enemies.
- The portal will consume all pickups and trinkets in its path, converting them into blue flies and causing the familiar to become larger and deal more contact damage.
- Lil Portal deals contact damage equal to (2x consumables destroyed count + 2), and ticks up to 10 times per second.
- When the familiar consumes four pickups, it will summon a portal that leads to an unexplored room on the current floor and its damage bonus is reset.
Notes
- Lil Portal doesn't consume pickups or damage enemies it passes over while trailing behind Isaac; it only does so while being launched.
- Lil Portal cannot be launched over Rocks or Metal Blocks.
- The room portals take Isaac to is determined at the time they're created; if Isaac clears the room the portal would take him to, he will still be taken to that room if he uses it.
- If every room has been explored, portals summoned by the familiar will do nothing and Isaac will jump up and down in them in a purely cosmetic effect. Same effect occurs if a portal is summoned in rooms that doesn't appear on map, as Mom's Heart room in (Mausoleum) Mausoleum/(Gehenna) Gehenna II.
- Portals can lead to (Curse Room) Curse Rooms, forcing Isaac to take damage in order to leave.
- (Secret Room) Secret Rooms and (Boss Challenge Room) Boss Challenge Rooms can be entered for free by making a portal after all other rooms on the floor are cleared.
- Portals will persist after Isaac uses them or leaves the room, and will always lead to the same room.
- Portals do not respect pathing rules, and can spawn on single-tile walkways and in front of doors, forcing Isaac to use them and preventing him from leaving the room through that door. This can cause a softlock depending on what door it blocks and where the portal leads.