Time beast

As you warp the Threads of time you summon a beast of lost in the sands of time  with a cr rating of 1/2 and for every higher slot you cast this at the CR will increase this beast will serve you for 24 hours and in which case you can command it to stay with out cost of a spell slot this will require a dc 12 int saving throw and the dc will go up by 1 with every success