The world championship cards you see on the first picture you posted, are hard to price as they are very limited and exclusive (No more then 3-6 copies in the world.) Only the Asianyensation himself would know
Basically, they make it so that both spells and abilities that your opponents control cost an extra two mana to cast or activate if they target a Merfolk you control
Photos of uncut sheets, which are quite abundant for the WOTC era but rare for sets released by Nintendo/TPCI, give exact information on rarities of individual cards
Umbra armor has no effect if the enchanted creature is put into a graveyard for any other reason, such as if it's sacrificed, if the "legend rule" applies to it, or if its toughness is 0 or less
Chandra, Hopes Beacon Chandra, Hope's Beacon is yet another 6-cost Chandra that comes in at five mana
BAM , had a really interesting (and sometimes confusing) story, the story didn't really matter as the gameplay was the most enjoyable part of it
