This appendix describes important card interactions that may not be obvious to a DDFT beginner.

Your Interactions

CardInteraction Notes
Act on ImpulseExiling cards doesn't count as drawing, so you cannot lose (or win) by casting an AoI when 2 cards remain in your library. Cards exiled with Act on Impulse can be cast, but their activated abilities cannot be used. For example, a Street Wraith cannot be cycled from an Act on Impulse exile.
Conjurer's BaubleOnly target a card if you must, never do it just for value, because if the targeted card is removed from the graveyard by your opponent then the bauble activation will fizzle and you will not draw a card.
Chromatic SphereChromatic Sphere's activated ability is a mana ability. Mana abilities do not go on the stack, therefore your opponent cannot respond to this activation. Chromatic Sphere allows you to play around creature removal with Laboratory Maniac piles because you can play Chromatic Sphere, Laboratory Maniac, and then activate Chromatic Sphere without your opponent having priority to cast their removal.
Lake of the DeadLake of the Dead does not enter the battlefield until after a swamp is sacrificed. Therefore, it is not possible to do any tricks like activating it in response to that trigger. You really do need 2 swamps in play in order to activate this card, and those swamps will be destroyed by playing and activating it. Lake of the Dead's activation is a mana ability and does not go on the stack.
Lion's Eye DiamondAs in any Storm deck, LED can be cracked in response to cantrips such as Brainstorm, Ponder, Preordain, Gitaxian Probe, and Conjurer's Bauble. Holding priority while casting these cantrips, by announcing "Brainstorm, holding priority," or holding the Control key on MTGO while casting Brainstorm, will allow you to crack the LED and discard your hand but still have the mana as you draw in to the next card of your library. Failing to announce that you are holding priority allows your opponent to say "OK" and then you will draw your next card and not have the mana from LED and have no way to get that mana without discarding your newly drawn card.

Opponent Interactions

CardInteraction Notes
FlickerwispAn opponent can cause headaches with an Aether Vial on 3 and a Flickerwisp in hand, since they are able to Exile cards at critical times in your sequencing. The disruptive cards that Flickerwise can exile are LED, Conjurer's Bauble, Chromatic Sphere, Laboratory Maniac, or a Land in response to an unresolved Rain of Filth on the stack.
Aven MindcensorIf there is an Aven Mindcensor on the board, a resolved Doomsday will be able to search only the top 4 cards of the library and the entire graveyard. Selecting 1 card from the top 4 does not allow you to dig one deeper in to your library.
Pithing NeedlePithing needle cannot stop LED, Lotus Petal, Chromatic Sphere, or Doomsday (players try naming Doomsday due to the strange wording on the Weatherlight printing since it appears like activated abilities do.) Pithing needle can stop Conjurer's Bauble and Fetchlands.
Phyrexian RevokerPhyrexian Revoker can stop LED, Lotus Petal, Chromatic Sphere, or Conjurer's Bauble. It cannot hit Doomsday or Fetchlands.
Grindstone, Predict, Thought Scour, Surgical ExtractionThese cards have the ability to disturb the ordering or contents of your library at instant speed, when you draw in to your pile.
PortentCan reorder your library at sorcery speed. Interferes with PTT piles.
StifleCan stop Conjurer's Bauble activations, Tendrils of Agony and Empty the Warrens Storm triggers, and Fetchlands. Does not stop Chromatic Sphere, Lake of the Dead, Rain of Filth, Lotus Petal, or LED.