+1: Look at the top five cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
−1: Target artifact becomes an artifact creature with base power and toughness 5/5.
−4: Target player loses X life and you gain X life, where X is twice the number of artifacts you control.
6/1/2011 The artifact targeted by the second ability will retain any types, subtypes, or supertypes it has. Notably, if an Equipment becomes an artifact creature, it can't be attached to another creature. If it was attached to a creature, it becomes unattached.
6/1/2011 If the target of the second ability is already an artifact creature, its power and toughness will each become 5. This overwrites all previous effects that set the creature's power and toughness to specific values. Any power- or toughness-setting effects that start to apply after this ability resolves will overwrite this effect.
6/1/2011 Effects that modify that creature's power or toughness, such as the effects of Giant Growth, will apply to it no matter when they started to take effect. The same is true for counters that change the creature's power or toughness (such as -1/-1 counters) and effects that switch its power and toughness.
6/1/2011 The number of artifacts you control is counted when the last ability resolves, not when it is activated.
7/1/2013 Planeswalkers are permanents. You can cast one at the time you could cast a sorcery. When your planeswalker spell resolves, it enters the battlefield under your control.
7/1/2013 Planeswalkers are not creatures. Spells and abilities that affect creatures won’t affect them.
7/1/2013 Planeswalkers have loyalty. A planeswalker enters the battlefield with a number of loyalty counters on it equal to the number printed in its lower right corner. Activating one of its abilities may cause it to gain or lose loyalty counters. Damage dealt to a planeswalker causes that many loyalty counters to be removed from it. If it has no loyalty counters on it, it’s put into its owner’s graveyard as a state-based action.
7/1/2013 Planeswalkers each have a number of activated abilities called “loyalty abilities.” You can activate a loyalty ability of a planeswalker you control only at the time you could cast a sorcery and only if you haven’t activated one of that planeswalker’s loyalty abilities yet that turn.
7/1/2013 The cost to activate a planeswalker’s loyalty ability is represented by a symbol with a number inside. Up-arrows contain positive numbers, such as “+1”; this means “Put one loyalty counter on this planeswalker.” Down-arrows contain negative numbers, such as “-7”; this means “Remove seven loyalty counters from this planeswalker.” A symbol with a “0” means “Put zero loyalty counters on this planeswalker.”
7/1/2013 You can’t activate a planeswalker’s ability with a negative loyalty cost unless the planeswalker has at least that many loyalty counters on it.
7/1/2013 Planeswalkers can’t attack (unless an effect turns the planeswalker into a creature). However, they can be attacked. Each of your attacking creatures can attack your opponent or a planeswalker that player controls. You say which as you declare attackers.
7/1/2013 If your planeswalkers are being attacked, you can block the attackers as normal.
7/1/2013 If a creature that’s attacking a planeswalker isn’t blocked, it’ll deal its combat damage to that planeswalker. Damage dealt to a planeswalker causes that many loyalty counters to be removed from it.
7/1/2013 If a source you control would deal noncombat damage to an opponent, you may have that source deal that damage to a planeswalker that opponent controls instead. For example, although you can’t target a planeswalker with Shock, you can target your opponent with Shock, and then as Shock resolves, choose to have Shock deal its 2 damage to one of your opponent’s planeswalkers. (You can’t split up that damage between different players and/or planeswalkers.) If you have Shock deal its damage to a planeswalker, two loyalty counters are removed from it.
7/1/2013 If a player controls two or more planeswalkers that share a planeswalker type, that player chooses one of them and the rest are put into their owners’ graveyards as a state-based action.