Nuevas Mecanicas
502.76. Prowl
502.76a Prowl is a static ability that functions on the stack. "Prowl [cost]" means "You may pay [cost] rather than pay this spell's mana cost if a player was dealt combat damage this turn by a source that, at the time it dealt that damage, was under your control and had any of this spell's creature types." Paying a spell's prowl cost follows the rules for paying alternative costs in rules 409.1b and 409.1f-h.
502.76b If a source that assigned combat damage left play before combat damage resolved, its last known information is used to determine its controller and its creature types.
* At the time you play a spell that has prowl, you look back over the course of the turn to check if the prowl condition has been met. What matters is whether you controlled a permanent with any of the relevant creature types at the time it dealt combat damage, or whether you controlled such a permanent at the time it left play and its combat damage was on the stack. It doesn't matter whether you still control the permanent or if its creature types are still the same.
* Playing a card for its prowl cost doesn't change the timing of when you can play it. Only the cost is different.
* Although the prowl reminder text lists specific creature types, this is done for convenience only. The prowl card's current creature types are what actually matter. For example, if a card such as Conspiracy causes a prowl spell to be an Elf, then you can pay its prowl cost rather than its mana cost only if an Elf you controlled dealt combat damage to a player that turn.
* Prowl is optional. If you want, you can pay a spell's normal mana cost rather than pay its prowl cost.
* Some prowl cards have comes-into-play abilities or additional effects if their prowl costs were paid. You'll get them if you played the card by paying its prowl cost rather than its normal mana cost.
502.77. Reinforce
502.77a Reinforce is an activated ability that functions only while the card with reinforce is in a player's hand. "Reinforce N--[cost]" means "[Cost], Discard this card: Put N +1/+1 counters on target creature."
502.77b Although the reinforce ability is playable only if the card is in a player's hand, it continues to exist while the object is in play and in all other zones. Therefore objects with reinforce will be affected by effects that depend on objects having one or more activated abilities.
