Let the monster loose: huge trampling creatures that punch through blockers and trigger on connecting.
Sets your commander and theme, then adds about 25 cards that fit plus 20 lands. You fill in the rest.
The top 40 of 560 cards that fit

#1,127$5.77Chris Rahn

#6,710$4.86Kev Walker

#21,096$5.33Aleksi Briclot

#2,515$6.16Kevin Sidharta

#1,591$16.75Lucas Graciano

#643$2.96Svetlin Velinov

#2,256$1.28Nicholas Gregory

#459$1.02Johann Bodin

#3,966$0.14Lars Grant-West

#2,428$1.31CatDirty

#1,862$0.25Ryan Yee

#10,559$0.13Zack Stella

#1,773$36.88Loïc Canavaggia

#7,889$0.35Jaime Jones

#10,930$0.59Karl Kopinski

UnrankedCristi Balanescu

#2,265$2.89Michal Ivan

#2,177$0.35Deruchenko Alexander

#528$1.03Daniel Landerman

#12,932$0.19Tyler Walpole

#1,582$34.03

#20,085$0.26Vlad Petruchik

#7,927$0.13Volkan Baǵa

#20,487$0.34Antonio José Manzanedo

#1,015$0.69Lucas Graciano

#5,178$3.25Chase Stone

#3,846$0.27Daarken

#1,189$12.13Steve Ellis

#1,439$3.19David Auden Nash

#4,475$0.51Lucas Graciano

#2,646$2.18Ryota Murayama

#5,911$0.41Zack Stella

#10,302$0.28Zoltan Boros

#1,250$33.86

#6,905$2.83Mathias Kollros

#1,753$4.82Karl Kopinski

#2,473$1.35Heonhwa

#2,027$0.16Nils Hamm

#3,136$2.80Jessica Fong

#927$48.89Justine Mara Andersen