For the good stuff, please check out the Crowdsourced Sideboard Guide and various Tips and Tricks over on r/PonzaMTG.
But here are a few tidbits and edge cases:
Arbor Elf: His ability is not a mana ability, so we can't use it to pay costs while casting a spell or while another ability is resolving. This means we can use Arbor Elf's ability before activating Chandra's +1 (Exile the top card of your library. You may cast that card ...), but not during it.
Beast Within: If the target is legal but is not destroyed (e.g., if it gains Regeneration or Indestructible), its controller still gets the Beast token.
Bloodbraid Elf:
- If possible, cast her before playing our Land-for-turn, in case we Cascade into a Tireless Tracker.
- We can use Fetchs to reshuffle our library after we Cascade needed high-CMC spells to the bottom.
- Keeping a Fetch uncracked when Courser of Kruphix is in play is great too, so we can shuffle away an unwanted Cascade card, if desired.
- She's VERY good vs. Control. Forcing them to chose whether to counter the Cascade spell or BBE (because they generally don't have the mana or spells to counter both) is just a GREAT feeling.
- Our Cascade spell resolves first, then Bloodbraid. This is especially relevant if we Cascade into Anger of the Gods ... Bloodbraid resolves second, so she takes no damage from the Anger.
- Because we "Put the exiled cards on the bottom of your library in a random order" after Cascade, we have to offer our opponent a chance to shuffle them too.
Chameleon Colossus:
Chandra, Torch of Defiance: Her Emblem is colorless, which is relevant vs. Protection from Red effects (e.g., Story Circle). Watch out though, because her Emblem is not a 'may' effect, which makes it TERRIBLE if your opponent has Leyline of Sanctity in play and there are no Creatures on board.
Inferno Titan: Its Attack trigger is not a 'may' effect, which can be troublesome if your opponent has Leyline of Sanctity is in play and there are no other Creatures on board. Though you can always target the Titan itself.
Primal Command: Because we have to resolve the modes in order, we can also bury things deeply with Mode-2-then-3 (bounce a thing to library, then make opponent shuffle), and pull critical one-ofs out of our graveyard with Mode-3-then-4 (shuffle our 'yard, then tutor a creature).
Trinisphere:
- As a general rule of thumb, when Trin' is in play, your opponent has to pay at least to cast a spell.
- Cost Reducers: Ruling #1 on Gatherer explains that Trin's ability is applied after any other cost increases or cost reductions. For example, even if the opponent has Goblin Electromancer on the battlefield, Pyretic Ritual costs .
- Suspend: Trin' does not affect the cost to Suspend a card (because it's not cast), but it does affect it when it comes off Suspend (because the spell is then cast for an alternative cost of nothing). E.g., Ancestral Vision costs to Suspend and when it comes off Suspend. Heh!
- Phyrexian Mana: Paying Life does not count towards the Trin' tax. E.g., Gut Shot costs 2 Life + or . Here's some more info from MagicJudges.org
- Delve: Since exiling a card from the Graveyard pays for , Delve does count towards the Trin' tax. E.g., Casting Become Immense for five Exiled cards and is the same as paying , so Trin' will not apply an additional charge. Here's some more info from MagicJudges.org.