Sandsteppe Mastodon

Reach is a static ability.

A creature with flying can’t be blocked except by creatures with flying and/or reach. (See rule 509, “Declare Blockers Step,” and rule 702.9, “Flying.”)

Multiple instances of reach on the same creature are redundant.

“Bolster N” means “Choose a creature you control with the least toughness or tied for least toughness among creatures you control. Put N +1/+1 counters on that creature.”