The addition of vigilance makes it that much stronger, but can block an additional creature each combat is such a unique effect, and in the format where most people claim to slot cards for redundancy, or still wrongfully cling to the 8x8 theory , youd expect High Ground to show up more
Being able to control what cards you get is really helpful, especially early on, and getting the right song at the right time could really change the pace of a game - plus, if you get a high cost song, you can easily sing it next turn once her ink is dry
In all other zones rules refer to the creature cards
Killing the summons before they sacrifice themselves sounds like a waste of a removal spell, but when that removal comes as a free bonus on a creature, it doesnt feel quite so bad
Bracket assignment checks for mass land denial, extra turn cards, 2-card infinite combos, and game changer cards per the Commander RC guidelines