After some researchs, i list here some creatures i could consider :

Instant Speed Creatures :

Ethersworn Shieldmage : even if a don't play artifact creatures, this card can block like an indestructible for 3

Darksteel Sentinel : the same use, for 6, but indestructability lasts and the card has vigilance

Dawnfluke : even for its evoke costs : can save a creature, and make a draw for 1

Restoration Angel : a good blink effect, if needed

Seht's Tiger : can be very powerful against a monocolor deck

Silumgar Sorcerer : seems a good option... even allowing me to sacrifice my creatures producing token or effects when dying.

Vendilion Clique and Venser, Shaper Savant are good control cards here two... but i don't have these cards.