Viability really depends on specific targets at each cost tier. Obviously most effect sac targets are rebirth minions and spent OG minions (and ideally ones that have survived a combat round already), most of which are a 2 drops (and partly since you already want to be playing 2 drops/4 drops for efficient openings with Flash).
However, at 3 and 4 cost there’s a lot of “okay but not great” minions and several which are effectively vanillas.
Realistically you need to sac something that costs 4 or 5 to ensure you get a good pull; which is a problem since you tend to want those to stick on the board. The best target is probably Elucidator; but there’s the question of whether you want to Cascade it for something vs leave it on board to force another trade. Odds are you’d get more value and options just throwing a buff spell on most minions you’d want to play this on, which is a bit unfortunate since I love these type of effects in other games.
I almost think that this card needs to have some additional bonus (and maybe cost a bit more) like giving the summoned minion Frenzy or Grow (or just +1/+1) for it to be definitely worth playing.