Artificer

create a 0/0 construct with this creature
gets +1/+1 for each artifact you control
Level 2: {4}{u/r}
{4}{u/r}: draw a card for each artifact you control
Level 3: {5}{u}{r}
{5}: create another construct
Level 4: {5}{u}{r}
{5}: untap target artifact
Level 5
artifact spells cost {x} less to cast where
X is the number of artifacts you control