I've had more success by including additional characters, which increase the chance of curving out perfectly and are generally better draws in the late game
If youre using Ursula, Deceiver of All, to sing song cards costing three or less ink - such as Friends on the Other Side and Bear Necessities - then youll be able to perform their abilities twice in succession, which is possibly game changing
And then you can play out a bunch of elves and win with something like Craterhoof Behemoth, or typal lords like Elvish Champion and Elvish Archdruid buffing all your creatures
In lower power brackets, Kefka can work as a combo enabler for Waste Not, an enchantment that makes its user create a 2/2 zombie token every time an opponent discards a card, which can be every time that Kefka attacks or enters
Walking Ballista was first released in the set Magic Online Promos, illustrated by Daniel Ljunggren