Note: Currently observing 1.11 Fast Learner buff to tweak this
In 20-room runs (castles/tower/events), this is the rule of thumb I currently use for important runs (where the choice of perks can impact whether I succeed or not)
- For Perk 1-3, take Fast Learner unless Homing or Multishot is offered; I will take it over desirable perks like Bouncy, Chain and Spread because they are more common and I expect I will get them again since I will be getting 3 perks in exchange for using 1 roll for Fast Learner.
- For perks until the end of room 9 (this seems to guarantee getting to at least 12 perks), take Fast Learner, except
- Take Homing, Multishot, Bouncy, Chain, Spread (1st or 2nd), Shrapnel / Piercing Shrapnel / SideWinder, Zap, Ice / Improved Ice, or Double / Triple
- Take Vertical, Back Shot or 3rd Spread if I already have Bouncy (they are not so useful without it and the chances of getting Bouncy in the rest of the run are now low). Would also take Vertical if I had Super Homing
- Take Frag Bullets if I had 2 (or more) Spread Shots
- Not decided if I should also take Fire/Poison/Flamethrower as the elemental damage has been buffed
- From Room 10 onwards (probably won’t get an extra perk but might advance the perk rolls) only take it if
- Alternatives are farming perks (crafter, hoarder/croesus, treasure hunter, haggler)
- Alternatives are jumping perks (triple / jetpack / springs) when I already have one of them (I haven’t mastered the use of balloon, and find I myself inadvertently sticking to walls with Ninja, so I avoid them both).
- Alternative is Dodge / Adrenaline (my base dodge chance is high, especially when playing Firebug; so I will take one of Dodge / Adrenaline if playing with other heroes + Necro but not otherwise)
- Alternative is health perks (Max Health Up, Tank, Combat Medic, LifeSteal, Band Aid) and I’m at a level where 1-2 shots will kill me. At lower levels I’m sometimes playing with Jackbot or playing carelessly, so health perks can help.
It’s a similar principle in 30 room runs, but I haven’t yet figured out the equivalent of Room 9 for that.
For endless runs: Take it only if the other perks are garbage - on long runs you don’t get an extra perk, and the advantage of getting the perk early diminishes (the higher you go, the smaller the advantage)