This isnt the first time, and likely wont be the last, that I reference the semi-finals match from #SCGCOL that Brennan DeCandio was able to win almost singlehandedly on the back of Walking Ballista: There is a point in this game in which Brennan has enough mana to beat Hunter while hardly attacking
My dad collected sports cards and was taught to sleeve my cards, but I put them in binders and boxes
They gain vigilance, indestructible, and haste until end of turn
The cost is a bit steep as youll need to keep your Harmonized Trio around and tap two untapped creatures, but I can see it being particularly useful in Izzet spellslinger decks where you need regular small spells
If WotC were willing to risk permanently and dramatically changing all future games of Magic by introducing Companions, then there shouldnt be much of an argument about making single-use, bankable mana tokens a part of most every game going forward