mtg arena symbols on cards Mana Chart What is this little symbol

Today I pause and a look at how this mechanic came to be and what it's trying to fix

I think this concept has a nice parallel to prices on MTGO

If the target player is an illegal target when Splinter's last ability tries to resolve, it won't resolve and none of its effects will happen

Brawl Not Legal Vintage Legal Timeless Not Legal Commander Legal Pauper Legal Oathbreaker Legal Penny Not Legal Toolbox Notes and Rules Information for Amoeboid Changeling: If a creature loses all creature types but then gains a new creature type later in the turn, it will be that new creature type

Its only really playable in Commander if youve got tons of synergy to back it up