A 4/4 creature is already big on its own, especially if you arent prepared for it or youre just attacking with a smaller one
There are also creature-lands like Lair of the Hydra that have an activated ability that animates them into creatures, and some planeswalkers, including Gideon-type walkers like Gideon, Ally of Zendikar and Kaito, Bane of Nightmares, that have activated abilities or triggered abilities that let them become creatures
see what you find easiest to read and use during a match
Deck OverviewCommander: Yuriko, the Tiger's ShadowSneak around your opponents defenses and strike with deadly precision
Her -2 filters through the player's deck for cards, like creatures that have their own venture effects
Full disclosure, I was absolutely stumped on how to approach this build