It can force a target creature to block, it can force a creature of the opponent's choice to block, or it can force all creatures to block
2016-01-22 Activating the second activated ability after a creature has legally been declared as an attacker or blocker won't change or undo that attack or block.
Most recently, Ive been playing Dimir Control
$2.49 Ultima (0328 - Borderless) Final Fantasy Variants $1.99 Jecht, Reluctant Guardian (0363 - Borderless) Final Fantasy Variants $0.69 Memories Returning (0331 - Borderless) Final Fantasy Variants $2.29 Kain, Traitorous Dragoon (0316 - Borderless) Final Fantasy Variants $1.79 Vaan, Street Thief (0390 - Borderless) Final Fantasy Variants $2.49 Summon: G.F
Fast aggro can run under her , and counters still matter
This means that Magic could see cards featuring fan favorites like Sephiroth, Vaan, and Clive