Albino Troll

If the effect of a resolving spell or ability regenerates a permanent, it creates a replacement effect that protects the permanent the next time it would be destroyed this turn. In this case, “Regenerate [permanent]” means “The next time [permanent] would be destroyed this turn, instead remove all damage marked on it and its controller taps it. If it’s an attacking or blocking creature, remove it from combat.”

If the effect of a static ability regenerates a permanent, it replaces destruction with an alternate effect each time that permanent would be destroyed. In this case, “Regenerate [permanent]” means “Instead remove all damage marked on [permanent] and its controller taps it. If it’s an attacking or blocking creature, remove it from combat.”

Neither activating an ability that creates a regeneration shield nor casting a spell that creates a regeneration shield is the same as regenerating a permanent. Effects that say that a permanent can’t be regenerated don’t preclude such abilities from being activated or such spells from being cast; rather, they cause regeneration shields to not be applied.

Echo is a triggered ability. “Echo [cost]” means “At the beginning of your upkeep, if this permanent came under your control since the beginning of your last upkeep, sacrifice it unless you pay [cost].”

Urza block cards with the echo ability were printed without an echo cost. These cards have been given errata in the Oracle card reference; each one now has an echo cost equal to its mana cost.