The collar's Attach cost is RR, Equip is 1, I made the changes for you
UUD
Swamp
Mindwhip Sliver
Done.
Turgy22: 20
Library: 28
Hand: 2
In Play
(TTT) Swamp x3
(T) Mountain
(T) Island ~mined 1 cntr~
Sparring Collar (Equipped creature has first strike; RR: Attach to target creature you control; Equip: 1)
(S) Burning Shield Askari (2/2; Flanking; RR: First Strike until EOT.)
(U) Wall of Shadows (0/1; Defender; Prevent all damage that would be done to this by creatures it's blocking; This can't be the target of spells or abilities that can only target walls.)
Graveyard: Dauthi Maruader, Ambush Party
RFG:
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Mooseman: 17
Hand: 3
Library: 30
In Play
(UT) Swamp x2
(UT) Mountain x2
(UT) Forest x2
Orcish Mine (When Orcish Mine comes into play, put three ore counters on it. During your upkeep and whenever target land becomes tapped, remove an ore counter from Orcish Mine. When the last ore counter is removed from Orcish Mine, destroy the land Orcish Mine enchants; Orcish Mine deals 2 damage to that land's controller.)
(U) Barbed Sliver (2/2, Each Sliver gains “2: This creature gets +1/+0 until end of turn.”)
(S) Mindwhip Sliver (2/2, Each Sliver gains “2, Sacrifice this creature: Target player discards a card at random. Play this ability as a sorcery.”)
Graveyard: Consume Strength
RFG: