Whenever you cast a spell you don't own, you may pay {1}{U}. If you do, put target nonland permanent on top of its owner's library. {2}{B}: Exile the top card of target opponent's library face down. You may look at and cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell.
Reading the Book of Secrets' chapter on “microtransactions” is strictly forbidden. Only Godmother Ilthiss may use the dark knowledge contained therein.
Flying Whenever you cast a cryptic spell, Guardian of Mysteries becomes a 4/4 Sphinx creature in addition to its other types until end of turn. (Artifacts, enchantments, and modal spells are cryptic.) {1}, {T}: Scry 2.
Flying As long as you control an equipped creature, Guide of Heroes gets +1/+1 and has first strike. As long as you control an enchanted creature, Guide of Heroes gets +1/+1 and has vigilance.
This spell can't be countered. Whenever one or more creatures with flying attack, upgrade Guided Sniper. (Give it one of the listed counters it doesn't already have.) • +1/+1 • Reach • Hexproof
You may look at the top card of your library any time. {T}: Reveal the top card of your library. If that card has a creature type no creature you control has, put it into your hand.
Creature spells you cast cost {1} less to cast for each of their creature types that no creature you control has. Whenever you cast a creature spell, if it has a creature type no creature you control has, draw a card.
Foresight — Whenever you draw your second card each turn, Haggler's Hound gets +1/+1 and can't be blocked by creatures with power 2 or less until end of turn.
Flying, trample Harbinger of Falling Skies enters with X +1/+1 counters on it. Whenever Harbinger of Falling Skies attacks, you may remove a +1/+1 counter from it. If you do, draw a card.
Choose one — • Target creature gets +1/+0 and gains indestructible until end of turn. • Tap target creature. Put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.) • Scry 1, then draw a card.
When Heirloom Seeker enters, you may search your library for an Equipment card, reveal it, then shuffle and put that card on top of it. Heirloom Seeker has first strike as long as it's equipped.
Flying Whenever Herald of Flame attacks, gain control of target permanent until end of combat. If it's a creature, you may have it become tapped and attacking. Whenever a creature you control becomes blocked, Herald of Flame deals 3 damage to the player or planeswalker that creature is attacking.